Product: Credit card or prepaid card

I had some other credit cards that were fraudulently opened in my name. I was a member of XXXX and was reporting those cards to XXXX  when I was discovered this card Discover was opened in my name. Discover card was the slowest to locate the documents that my XXXX agent sent ( the same documents she sent to the other 5 or 6 credit cards ). They said they had phone calls from my previous phone number ( my husband and I switched cell phone carriers ) like the other cards but these calls were NOT me. Someone had copied my phone number and acted like me on the phone. Discover asked me what email they should have on file. They had a XXXX but it was not mine. They did not tell me the email address..just confirmed that it was not XXXX. I do NOT have another XXXX account, just one.They also said that the statements were being sent to that email ( the one I did not know about ) and I told them I do not receive estatements for credit cards as I do not like it. I Discover is requiring documentation saying so ( our previous cell phone carrier was not corporative and we can NOT get the documentation that Discover needs to relook at my account. The documentation needs to say our account with the cell phones was compromise and the company will not admit ). Discover called me and claimed to have talked to me about a person that was an authorized user on the account but they did not. That day they called, was the ONLY time I didn't talk to them with XXXX on the phone as well and all the Discover agent went over was the process that banks go through if someone comes in to get a cash advance. That is it. I tried ask Discover if they are not sure where the cards were sent, how are they sure if they came to my address? And how can they be sure if they talked to me on the phone since someone had acted like me and talked to the other credit cards. Discover has not responded to either question. XXXX is unable to further to assist me due to not being able to get the documentation that Discover requires to relook at my account. Now Discover is saying I'm responsible for the full amount on the account. These charges on mostly online or out of my state. I do not shop online unless its on XXXX. Most of my shopping is done in person where I HAVE TO SIGN ... very little do I shop online. I do not bank at any of the banks listed. I have told Discover that I DO NOT know either person that was listed as authorized user on the account In fact I did not know either name or that there were two authorized users until I was talking to my XXXX agent. A lot of the charges are for XXXX  which I do not, have never nor probably won't use. I have never bought anything from XXXX. In fact my phone I got was through a cell phone carrier. 
Discover also did not get any documentation from the banks where there was cash advances ... therefore I do not understand how they can be sure that it was ME who got them ( especially since I did NOT get the cards ), Discover is not giving copies of the documentation they used to determine this was not fraud which they have to by law. 

I personally feel that Discover did not take what I said seriously and really truly did not look at this account as fraud or that is was fraudulently opened and all of these charges, cash advances and balance transfers ( I do NOT know how to do a balance transfer ... nor have I ever done one and I have NO interest in doing one in the future ) are done by someone NOT ME. I expressed to them at least 3 times that I did not open this card or I did NOT apply for it. 
The charges on this Discover account were VERY similar to the other credit cards and the other cards saw that them was fraud. I do not understand why Discover said it was not. 
I should not be responsible for charges that I DID NOT DO. I