Product: Credit card or prepaid card

Citi charged me a foreign transaction fee on my Citi Double Cash Credit card, ending in XXXX, with no references to the original transaction and wasn't able to locate or explain the original transaction. In the interaction that ensued with their support rep, I was told that A ) I was charged in a non-existent currency B ) The bank does not record all the details about the transaction and is unable to provide them to me Transaction details, as posted in my account : FOREIGN TRANSACTION FEE {$0.00} Transaction Type : Fees Posted Date : XX/XX/XXXX Reference Number : XXXX I called their support number ( XXXX ) and spoke with a representative, asking to provide me the information I would need to locate the transaction this was related to. The representative told me the fee was for a transaction I was charged by XXXX, for the ride I took in the XXXX on XX/XX/2018, and the currency they charged it in was " Florian '' ( that currency doesnt even exist, Florin was one of the names for the XXXX currency before they transitioned to Euro 17 years ago! The rep even attempted to spell out the currency name, incorrectly ). 
When I explained that I was not in XXXX on that specific date, their first suggestion, instead of ensuring the accuracy of the transaction was to suggest I dispute it. I let them know that I didnt want to be banned by XXXX for disputing a valid transaction because Citi has failed to identify it. 
I asked for a reference number, given by XXXX, that I could use to locate this transaction by. The reference number I was given ( XXXX ) does not correspond to anything I have from XXXX. As I found out, by digging through my statement online, it was a Citi reference. Which is neither searchable in the online portal nor included in any emails, so is not helpful in locating the transactions. 
I asked for the amount in the original currency, so I could find the receipt from XXXX. I was told that it was XXXX " Florians ''. I have not transacted with ANY merchant in " Florians ''. I explained that I have taken XXXX and paid for it in XXXX, along the same dates, so if that was the transaction in question, I was expecting the currency for the XXXX transaction to show up as EURO. 
After being placed on hold, the representative went on to explain that, even though XXXX is part of the XXXX XXXX, and that they have accepted Euro as their currency, the merchant chose to charge me in " Florians '', since the transaction was originating in XXXX. 
They also told me they have NO WAY to see the transaction 's original amount, in the original currency. All they see is the converted amount in USD, once it is posted to my account, and the conversion rate for the original currency, that was effective on that date. The rep said they would need to calculate it out, which I asked them to do since that was the information I requested. I am highly suspicious of this claim that such an important part of a transaction isn't recorded, as I believe, for compliance purposes, a bank would need to record the original amount in the original currency, the conversion rate, effective on that date, and the final converted amount in USD. Having the bank admit that they don't do it is extremely concerning. 
Digging deeper into my statement, while still on the call, I was able to find the original transaction from XX/XX/18, in EUR, as I expected. The amount was XXXX EUR. Which is suspiciously similar to the amount they quoted in " Florians ''. 
I've asked the rep to confirm if they were able to see this amount and this currency on their end. They were not. They also couldn't explain why but they were showing a transaction in an ancient/non existing currency that I DIDN'T pay it in. 
My previous 4 or 5 calls to Citi support were all related to international transaction and not a single call was resolved. In fact, in every interaction, they were completely incompetent, as the bank, and their reps included. Which I mentioned to the rep I spoke with. 
This was the last drop, and as the result, I will be closing my account with Citi that I've had for 12 years.