Product: Debt collection

I have been a XXXX customer for almost 7 years now. I currently have XXXX phone lines on my personal account and always have paid my phone bills on time. In XXXX 2016 I had purchased XXXX phones from XXXX, on XXXX of those phones I added a new phone line. The sales representative who was helping me out was new and made many mistakes while helping me with this transaction, the first XXXX being is that she accidentally opened up a new XXXX account instead of just adding the new phone line to my current account she opened up a new one and applied the fees to the new line that I was adding to the account she opened up with out my authorization. the second mistake she made is that she some how switched the serial numbers to the phones so when we made a phone call to one of the phones the XXXX rang instead and vise versa. This was critical because when she realized that she had opened up a new account instead of just using my current one she never took out the fees to the brand new I phone 6 plus that I had purchased. Instead what she did is she closed out the account and left the phone fees in there which was {$740.00}. After being there for several hours trying make sure everything was okay with both the phones i had purchased she had assured me everything was good to go and I should not have anything to worry about. 7 months later i get a call from a collections agency saying that I owe XXXX {$740.00} dollars. during the 7 moth period that I supposedly was not paying for my phone, I was under the impression that i was paying for XXXX the new phones i had purchased and the new line that was added to my account since my bill went up {$31.00} since i had made those transactions. Little did I know that XXXX of that phones that i had purchased was never getting paid for due to XXXX inability of making me aware of the situation until it was too late. Initially, when i first started investigating the situation I thought someone XXXX had committed fraud and had falsely used my information to buy these phones but after a more thorough investigation I realized XXXX was at fault for opening up a new account that I had never authorized to be opened up and left phone fees in there accidentally, that should have never been applied to a new account from the get go. Now, one can ask themselves? does n't XXXX have a process established to prevent a situation like this form happening? well yes they do, it turns out that after 30 days of non-payment on any phone line the phone/account should automatically stop working which if this would have been the case it would have notified me in enough time to prevent this major misunderstanding. However, remember how the sales representative accidentally switched the serial numbers to the phones that I bought on XXXX 2016 somehow XXXX system was not able to cancel my phone line due to the serial numbers being flipped flopped, which in my mind is the second major mistake that went wrong for all this to happen. Currently, I am in the process of buying a new home and due to XXXX inability to train there employees properly my credit score got hit with XXXX points since those fees have been in collections. I have been trying to resolve this issue with XXXX for several weeks now and twice they have told me i am responsible and they are not able to help me out. I am desperate at this point and need someone who can help me out with this situation. The collection agency who inaccurately has my debt is Amsher Collections XXXX XXXX XXXX XXXX XXXX, AL XXXX. XXXX Acct # XXXX