I am complaining about how XXXX is handling a mistake that they made which is affecting my credit, as they are not making any effort to resolve the issue after several months of attempts by me to get to resolved. All of the effort is on me to get them to fix their mistake. I already had XXXX service in XXXX with XXXX lines. After making sure the service worked OK, I ported my XXXX XXXX numbers to XXXX. In XXXX XXXX, I wanted to add a XXXX line to my Family Plan, where a XXXX line would be only {$10.00} per month, plus the cost of financing the cheapest smartphone ( adding about {$5.00} per month XXXX. I did this in a store. They made a mistake and created a new account instead of adding to my existing account. When I realized this, I called to get it corrected. Instead of moving the phone and service over, they billed me for the phone and calling plan in its entirety, as though I wanted a new phone and a one month plan. Even after XXXX months, that barely comes to {$170.00}, but their billing to me was for a single month of service and the phone. I called again and thought it was resolved. Meanwhile, the XXXX line was working on my Family Plan. Then, in XXXX XXXX, I got a collection notice. I will summarize the rest in saying I made literally hours of calls multiple times, and in XXXX cases got escalated to " supervisors '' that said they understood and could resolve the issue. Nothing has been done. XXXX reps claim that the charges have been " validated '', meaning they did nothing to look into it. XXXX isolates that credit group from the public so there is no way to speak with them, and there is no way to get it resolve. I have sent a written dispute and they changed to yet another collection company ( that is owned by XXXX ), and they are offering no time to resolution nor anyone to contact. After XXXX months and hours of my time, my credit is still affected and I can not make a home purchase. Their reps have no clue what to do, and their hidden " accounts receivable '' or " collection '' group does nothing. This should not be legal, and their mistake should not be my burden to exert such effort for. If I charged them how they charge me, they should owe me about {$150.00}. I am filing a complaint because there needs to be repercussions for this sort of behavior. My only other option appears to be suing them, but with that, there is no record of a consumer complaint. I have paperwork supporting my case.