How to unsync iPhone from old iTunes account?

Okay, so this is probably a simple question, but I'm having trouble figuring out how to do this.

So I downloaded a new iTunes with the same account as my old one and I synced my iPhone with it.

A window popped up 'Do you want to unsync from old iTunes library?' I clicked YES

But now all of the songs that were on both libraries are duplicated on my iPhone (though duplicates don't show up on the iTunes account), like it's still synced to the old library. It's been like this for a few weeks now and it's annoying me and taking up double the space it should be.

How do I unsync it from the old library and just have it synced to the new one?

Is AT&T doubling the data that's ACTUALLY being used?

Okay so let me start by stating my current set up: iPhone 5s, AT&T, unlimited Text, Calls, 15gb month plan SHARED. Former setup: HTC Evo 4g, Virgin Mobile, Unlimited Data, Text, Calls.

My problem is this… My girlfriend, has the same phone as I do except she has one thing that I don't, Wi-Fi. She has it at home and at work so in reality, the 15gb data plan is pretty much all mine. The first month of AT&T service after switching from Virgin, we were on the 10gb data plan which we blew thru in about 8 days. Has to be some type of mistake right? Wrong. We were forced to switch to the 15gb plan. The usage was a few YouTube videos, Instagram, Spotify a few hours a day at the gym, a few game aps, eBay, Craigslist, the usual. Since then I have turned off everything including LTE (except for messages) deleted all apps and ONLY turn data back on things when I need them, use them for a sec then turn their data back off. We're now a week into the billing cycle and it looks like we're going to be close to going over. When I was on virgin mobile with unlimited data I was riding on 4g 24/7. I would have spotify on from the moment I woke up to the moment I got off work, I would watch continuous YouTube videos as well as play game aps. I would even watch netflix about 4 hours a night. I finished the entire series of DEXTER in ONE billing cycle. My data usage NEVER went passed 6gb of data and must I remind you I was never on Wi-Fi. Is AT&T Charging 3mb for every 1mb I ACTUALLY use?

How to get home sharing on my iphone?

I have recently just found out about Home Sharing and it sounded like a neat feature to be able to clear the music on my iPad 3 to regain space and also stream my movies, but I can't get it to work. On my computer (Windows 7 with latest iTunes), I have enabled home sharing and signed in with my Apple ID. On my iPhone, I opened Settings went to Music and signed in with the same Apple ID (I only have one). When I open either Music on my iPhone, I see nothing that would hint at sharing. No shared option in the "more" section of Music. All devices are connected to the same wireless network. I've tried turning off then back on again home sharing from itunes and neither setting worked. My web searches didn't find anything helpful either. What settings might I be missing to enable Home sharing. Itunes is 11.2 and iphone is 7.1.1

IPhone is disabled, won't restore with iTunes. How to completely wipe it?

My friend bought me this iPhone 5S he got. It looks brand new in a box with everything.
I can't get into because there's a passcode on it, he doesn't know the passcode.
The front screen says "iPhone is disabled connect to iTunes".
I connect to iTunes and a message pops up "iTunes could not connect to the iPhone because it is locked with a passcode. You must enter your passcode on the iPhone before it can be used with iTunes."
It's disabled, I can't enter a passcode even if I wanted too.
I've tried restoring it, holding the buttons down until the iTunes logo pops up.
I've tried it in recovery mode.
I've tried the emergency call trick, NOTHING is working!
Seriously, how can I get in? How to completely wipe it clean? I can't sync it with any computer.

Internet on my Iphone 4 so Slow?

Okay so I've noticed this has started like three weeks ago my internet being really slow, even downloading apps takes a really long time and sometimes i have to download them again because it fails. Loading videos especially is a problem. Youtube hardly works. I called mobile and they said its a upgrade thing bit i upgraded and restored to factory settings, rebooted even but still the same thing. I live near 3 cellular signal things so they said it should be perfect bit I've noticed at night it works almost perfect with no buffering. This is like 11pm onwards?

My iphone has more songs than Itune?

For some reason, my iphone has 964 songs when my itune library has only 419 songs, some of my songs in my iphone has a lot of duplicates and whenever i tried to delete them and sync again they just come back and also i noticed that whenever i click an option in the itune and my iphone summary bar music colour is reduced to the right amount but when i tried to sync it goes back to the same amount of 964.

I already tried to move the unnecessary songs and musics but they're still there in my iphone somehow returning when it was already moved to somewhere else.

Added (1). It's like as if itune didn't even attempt to apply the change at all.

Added (2). It's like as if itune didn't even attempt to apply the change at all.

Iphone 4 went black and won't turn back on?

So last night I took my phone off charge and it was working fine. The battery was at 60% and i put it on stand by and set it to the side while I put my hair up before bed. When I tried to wake it back up, nothing happened. Just a blank screen. Tried powering it on and off but nothing even showed up on the screen. Tried holding down the sleep and home button and putting it on charge but nothing changed. Didn't make any noise whatsoever. I left it on charge and about half an hour later it started booting up, showing the white apple screen. But then it stayed like that for at least 15 mins without change, so I took it off and held down both buttons until the screen turned black and kept holding the home button (took advice from an Apple forum.) I tried powering it back on but nothing changed. I put it back on charge last night and went to bed, hoping it'd be fine but nothing changed. I still have a black screen and no response whatsoever.

Added (1). Also, I have no USB cable so i can't computer restore it. I charge using a TV dock. I thought maybe it was the dock but my dad put his ipod on it and it started charging right away.