Product: Credit card or prepaid card

My problem is with a company called Barclaycard.

Their mailing address is : Barclaycard US XXXX XXXX XXXX XXXX, DE XXXX My account was hacked at least 4 times over a 2 or 3 year period. Several times the charges were from a travel agency of some sort. This information was on my statements. Every time this happened I would call them and inform them about the fraudulent charges and they would remove them from my account. Every time this happened they would cancel the card and send me a new one with a new account number. I would in turn have to notify every merchant/vendor that I used this card for payments and give them the new card number. I became weary of this process.

On one occasion they removed the charge but then put it back on the same day. Once I discovered this I called and they removed the charge again. This charge was for {$1400.00}. 
This all occurred in XX/XX/2018. That is when they removed the charge and put it back on and removed it again. Now they say I owe {$1400.00} because the account was credited twice, which it was because they removed the charge, added it back and then removed it again. 
On another occasion I had some reward points to cash in but found out that the account had once again been compromised and they sent a check to someone in New Jersey. 

I finally got tired of the problems and obtained another credit card from another provider ( XXXX  XXXX ) and I called Barclaycard to  find out my final balance so I could pay it but was informed that I had a credit for around {$200.00} for which they mailed me a check. Once the check arrived I closed the account. I don't have any documents to support my claim. 

I closed the account in XX/XX/2018 and in XX/XX/2018 they sent me a letter saying that I still owed them {$1400.00}. I called them and the representative told me the charge was from a travel agency. I was left with the impression that this would be corrected. Now the charges all say " Barclay Rewards ''. There is no record of charges from a travel agency. 

When I received another letter trying to collect {$1400.00} I called them again. I have spent many, many hours on the phone trying to resolve this issue. Now they say they can't find any record of a charge from a travel agency. Now they say the charges are from " Barclay Rewards ''. I asked them to send me some statements which would have covered the period in question and there is no mention of a charge from a travel agency. The charges all say " Barclay Rewards ''. It is as if they have gone and removed all traces of the charge from a travel agency. 

On my last call I was transferred to a supervisor and then to a higher level supervisor who said she removed the charge and that I had a XXXX  balance. I think she lied to me just to get me off the phone because she was tired of listening to me. 

A week or so later I received a letter saying that I still owe this money. 
I don't know what else to do ; If I don't pay the bill it will affect my credit report but I don't want to be bullied into paying something that I don't owe. 

There is something seriously wrong with this company. I have never had a credit card hacked before or since my experience with Barclaycard.