Product: Credit card

While traveling on a trip to see my kids at their colleges in XXXX of XXXX, the pet sitter we used from XXXX XXXX XXXX stole my new unused Athleta card from my mail. I NEVER used this card and the card was stolen from my home in its original envelope from XXXX. Because that was all that was stolen I did not know it was gone from my files. The thief contacted XXXX to change my contact information, therefore notification of the fraudulent use of my card was not known to me until XX/XX/XXXX. I immediately called XXXX XXXX XXXX to report the theft. I spoke to XXXX XXXX in XXXX Collections who transferred me to XXXX in XXXX XXXX XXXX. he stated my card had been used to charge {$3400.00}. I asked XXXX to close my XXXX XXXX account and to block any further use of it to avoid any further problems with XXXX. XXXX went through each of the charges and asked me to say whether or not each charge was mine and I stated I did not make any of the charges as I had never used the card. I asked to be mailed a statement as I had never seen nor expected a statement as I never had used the card. He stated that the investigation team would investigate and get back to me by XX/XX/XXXX until the investigation is closed that it would be resolved. On XX/XX/XXXX I received notice that the case was resolved. I thought at that time that the issue was done. XXXX had stated that Barclays would contact the credit rating companies to correct the report. 
This case resulted in my excellent credit rating downgrade due to negative hit from past due bill since the credit card company did not suspend the charge while investigation was ongoing. I had filed an identity theft report with the Federal Trade Commission ( FTC ) to report the incident and protect myself from identity theft should something arise in the future. The reference number is : XXXX. 
I contacted Barclays on XX/XX/XXXX and spoke to an agent named XXXX after I was contacted by XXXX XXXX a collection agency, stating that my account was sold to them for collections. XXXX at Barclays stated that there were a few charges they needed me to confirm that I hadnt charged and were fraudulent which I did. I asked XXXX to send me written motivation of the status of the investigation and for a reason the account was sold to XXXX XXXX before the investigation was complete. I have not received anything from XXXX telling me about their investigation. There is no way there is any substantiation that these charges are mine. Prior to this issue I have had an excellent credit rating. On XX/XX/XXXX I contacted Barclays again to find out the outcome of the additional investigation charges and spoke to agent XXXX  who initially had no information, but said I should contact another number which I saw was XXXX XXXX  I asked to speak with a supervisor and was told there were none available. I asked him to have a supervisor contact me and he said he would put in a follow up but would not explain how I would be contacted. Because I have received no info other than my case was concluded and written off by XXXX, I am concluding that my case was never investigated before being sent to collection. Because if it was investigated they would find that the charges were not made by me. Id like to note that my research shows that the Consumer Financial Protection Bureau took action against XXXX XXXX XXXX and ordered them to pay {$24.00} million dollars for violations of the law in collecting on unsubstantiated debt. I am appalled that there was no follow up or investigation done. 
Barclays has not worked with me in good faith now nor has been helpful at all during the process since I reported the card stolen in XXXX of XXXX. None of these charges are mine and I am concerned that my credit will not be corrected.