My iPhone charger only sometimes works?

My iPhone charger works fine, like I don't have to hold it in certain positions. But sometimes when I take it off the charger and put it back on, it just doesn't work. It'll start working again if I put a new jack on it or put it in a different outlet. Why does it do this?

How can I track my iPhone X preorder?

I preordered the phone via Verizon, but they do not update estimated delivery time as apple does… Is there any way I can use the Apple ID number or preorder number to track through Apple?

Sold a WORKING iPhone 7 plus on craigslist a month ago, now guy saying the phone is faulty?

So, i own a repair shop. The iphone needed nothing more than a new screen, so i changed the screen and met the guy at the at@t store and they did an inspection on it and said that the phone was good to go, next, a month later the guy calls me saying that the phone is faulty and has broken things on the phone, and if i don't refund him then he will be taking legal action. Is there actually something legally he can do? I don't know if he broke the phone now just wants money back? Things don't work like that… Could he sue me? Or would this be laughed at in court.

Iphone 7 won't respond to touch or turn off?

Starting yesterday it has been unresponsive. I can unlock it, but after that I can't go into any apps. If I ask siri to open an app it doesn't do it. I tried holding down the power button or the power/home button but nothing happens.