How to unlock iphone in another country?

Due to my last iphone breaking and costing more than it was worth to get it fixed, I decided to treat myself to an iphone 5s which I bought on eBay from a UK seller but it is locked to vodafone. I'm a vodafone customer in the uk and also in Spain, where I'm living for a year, but my UK sim is a micro sim and doesn't fit in the SIM deck. I'm not due back home till December so can't do anything about it.

The phone was wiped before being sent and when I put my Spanish vodafone sim in, which is pay as you go, I can't set the phone up as it says it's invalid. I don't know the account details of the last owner and don't really know what to do in order to unlock my phone to allow me to use my Spanish SIM.

Is my iPhone using mobile data?

So, I just recently (2 days ago) switched from a samsung to the new iPhone 6s and I'm wondering if the phone still uses up mobile data while wi-fi is on? I know that with Samsungs, if your mobile data is on and you're connected to wi-fi at the same time, then the phone will just use wi-fi. Is it the same with iPhones? I only have 10 GB of data per month and I need it when I'm out but I've realized I don't get picture messages or group messages unless the mobile data is on. Can I leave it on as long as I'm connected to wi-fi?

Is it free to use IMessage with your data internationally? Or is that only using Wi-Fi?

I have a friend who is from Canada and I'm from the US. And he has an iPhone and so do i. He said that we can text on our phones for free internationally using iMessage, but what I've heard is that it's only free if you're using Wi-Fi. What about your data? Is it still free when I go out and am away from Wi-Fi and use my data? My messages still appear blue when I message him with my data but I'm concerned that it's not completely free when doing so.

What would you do if this happened to you?

What would you do if this happened to you?

Added (1). What would you do if you heard on the news that there's a text code in Arab writing that's going viral for every iPhone version and it's known to crash iPhones and shut them off for 48 hours. So u blocked everey friend to make sure they don't get you with the prank.

But a random number comes out of no where and sends you the text for amusement and now your iPhone is off for 48 hours.

Wat would you do and how would you feel?

How to block No Caller-ID phone calls on iPhone?

Last night I got a call from "No Caller-ID". I didn't think much of it until it happened again, and again, and I woke up with 4 missed calls from them. They stopped and called again earlier this morning one time when I was sleeping, but I just forgot about it. They just called me again. What should I do?