Product: Credit card or prepaid card

I have been a Bank of America credit card holder for many years. 
I received a statement in XXXX this year showing a transaction of XXXX dollars charged to my credit card from XXXX, XXXX. 
Transaction date was XX/XX/XXXX and posting date XX/XX/XXXX. 
I visited XXXX in XXXX and I have not been out of country or in XXXX since then. 
I did not lose my credit card and it has been with me. 
I called the Bank on XX/XX/XXXX and talked for a long time and told the detail. 
On XX/XX/XXXX I received a letter saying that the card was used and chip was read that time and so it was a valid claim. 
I called the Bank at the # provided and they called back my cell #. 
I talked to the specialist and the supervisor as they allowed me to talk to for over XXXX minutes. I tried to talk to someone higher up in the authority who can help to further investigate this fraudulent claim but was not able to. 
I asked whether there was any transaction in that card in XXXX in XXXX but they refused to give me that information. 
I have not been to XXXX or anywhere else outside XXXX in XXXX or XXXX and the card was with me. So it was impossible to use my card in XXXX in XXXX XXXX. 
They could not explain how the chip was read or the card used when I had not been there and the card was with me and no duplicate copy of the card. 
They did not give me any convincing reason how it could be possible. 
They did not give any answer how they investigated the fraud claim and whether any federal or law enforcing agency was involved as this seems to me a certain fraud case. 
They could not explain why they approve a very unusual foreign transaction without verification and without contacting or verifying with the card holder. 
I always notify the credit card company if I am going out of State or out of Country, and they did not receive any such notifications / alert from me.

Given the unusual nature of this transaction I asked whether anyone in the company could be associated with this kind of fraudulent activity, which they did not answer and did not say whether any law enforcing agency involved in that regard. 
They said they would open another investigation to look into the matter. 
I received another letter dated XX/XX/XXXX saying that they found it was a valid transaction and the fraud claim was closed. 
Now given that I could not be there in XXXX to use my credit card and it was always with me, yet the company / Bank of America maintained that it was a valid transaction - it raised a serious question whether the credit card company be involved in this fraudulent activity and whether they or others involved in activities defrauding their credit card holders. 
I called the Bank of America again on XX/XX/XXXX and asked for my options and provide me with the names of the State and federal regulatory agencies or other Law enforcing Agencies where I can take this case for further review but I was told to XXXX it and they could not provide me any. 
They have defrauded XXXX dollars of me and foreign currency transaction fees with this credit card fraud and wonder whether this is a systemic issue with the credit card business. 
I will appreciate any of your help in this regard and also to further this with any Law Enforcing Agencies for a deeper investigation if and as necessary to protect us the consumers.