Angry CUSTOMER

Hi everyone I been with AT&T since maybe March of 2017 I agree to finance a total of 3 phones that I didn't have a problem with paying there was a tablet that was included into the deal for and extra $10.00 which was add on to my bill which turn out to be a total of $285.98. The tablet had 1GB which is  connected to my phone witch is unlimited I thought that means it is included with my unlimited package so I didn't pay attention. My little girl went over the 1GB which turn out to be over 15GB  so the bill turn out to be $1531.10 yes ridiculous I know I was shock myself I how to look at it like 7 times to make sure my eyes wasn't deceiving me so I call in spoke to a representative he even agree that it was crazy just how much they were charging me to make things more difficult for me my Wifi kept dropping so I how to have a tech to come out to replace the box.The Rep gave me a ticket number I ask will I be notify able what was going on, he told me yes I requested if they could leave me a Email because am always at work and I can't use my phone on the job he told me know problem they will send me  notice on the case, guess what no one sent information about my case I how to hound these people into telling me what's was going on finally Jessica at finance told me my case was close and the manger close the case WHAT!....she said sense I was sent notification about my data was over the limit that I new. I was shock in disappointed with them first is this how you AT&T treat there customer I thought the notification was weird sense I have the unlimited plan never in wildest dream that the cause of this was the tablet. There is no way I can pay this I should of stuck to my old phone company then going with AT&T.