Product: Credit card or prepaid card

Good morning, I have a concern and an issue I am dealing with and I would appreciate your help. I have a credit card through XXXX XXXX in which I am having the issue. 

The issue : In approximately in XXXX, they reached out to me and asked if I would be interested in 3 months of deferred payments and if that would help me out during this strange time we are in. I did accept their offer as it definitely would help me out as the monthly payment was about {$400.00}. They did say my card would still earn interest, which I was ok with. I was told that my next payment would be due on XX/XX/2021 in the amount of {$390.00} but I did need to get my account up to date as I was behind {$77.00} in which I was able scrounge up and get to them within a couple of days. I was told to ignore any automated phone calls and the billing statement as we go through the next 3 months. 

Within the 2nd month XXXX XXXX week of XXXX ) I was getting multiple phone calls and decided to give them a call to see what was going on. I was told that they were going to send my information to collection if I did not pay my credit bill. As the gentleman that I was speaking with looked into the situation, he saw that I shouldnt have not been receiving calls and fixed the issue, also explaining to me that my next payment is due on XX/XX/2021 needs to be in the amount of {$390.00}. I did receive a bill showing this amount early XXXX. 

I now received a phone call saying that I have a late payment and the {$390.00} they received on XX/XX/XXXX was short. I need to make an additional payment of {$800.00} XXXX and change ) for interest and late charges. I asked to speak with a XXXX as this made no sense to me. Why would you defer my payments for 3 months and then hit me with a huge payment at the end of three months. I did miss a phone call from Barclays bank XXXX XXXX XXXX ) but could not talk with them at the time they called yesterday. I am getting nowhere with the multiple people I have talked with and keep getting the run around. I requested to talk with a manager and still have not been able to talk with one. Each time I talked with anyone I asked if they could look at my notes on my file and even though they say they add notes, nothing is there. I did mention to the last gentlemen that I talked with to add the note that I need to speak with a manager and as they say we record our phone calls I asked to pull the recorded phone call prior to the manager calling me. At this point nobody has returned my call. I did ask that they take me off the list for the repeated phone calls and will wait for a manager and he said we would. 

My concern : I have never asked for any help in these times, and my family and I worked hard together, matter of fact my son wanted to start unemployment and we had a long talk and worked together to get thru a major bump in the road and to get him working again. I understand the hardship, but I can only imagine what the banks are telling you and what they are really doing. The additional stress they are putting on myself along with other people ( I would assume ) is unnecessary. 

I really need your help in this matter. 
Thank you in advance