Product: Credit card or prepaid card

This is a problem that started in 2020. I have since tried to get help. I called the company for over a year and stopped when they sent my account to debt collection and tarnished my credit score. I finally gave up until I found this. So in 2020 I started using my credit card again and made some purchases here is where everything fall apart. Using citi double cash banking app I put in my banking information and made a large payment of {$500.00} at the time. The credit company rejected my payment. I was confused and opened the app. They tried to withdraw the payment from a different bank and an account that I dont own. I dont even know how that is possible. I called them the first person I spoke to a man was quite frankly rude. I explained that I used the app to make my payment but that they tried to withdraw funds from a different bank. I asked how is that even possible. I was told in a very rude way that the it was impossible and that I made the mistake. I told him that on the app the only bank account listed was my bank and I wanted to know how they withdrew funds from a different bank that I dont own. The man told me that it was my fault and the call was disconnected ( honestly I think he hung up on me ). I reprocessed the payment the same way I did it the first time and it went through within 24 hours they collected my payment and closed my account. I called again and was told again that it was impossible for them to withdraw from a different bank and that the mistake was mine I dont have an account with that other bank. I asked why my account was closed and that I wanted this resolved and I was told that it was illegal for them to speak with me about my account but that they would not mind a payment for my account. I only paid part of my account. They told me that I would receive a letter in the mail explaining why my account was closed. For six months I was calling every few days. During this time I never received a letter in the mail. Every time I called I was told that it was illegal for them to talk to me about my account. They told me to wait for a letter and every time asked me to make a payment. After six months I told them that if its illegal for them to speak to me about my account then its illegal for me to pay it until someone can talk to me. I was calling about once a week for over a year and each time I got the same response ( its illegal for us to talk to you about the account but we are willing to take a payment from you. Also please wait for the letter in the mail ). Each time I was stonewalled, finally after a year waiting for a letter I received on in the mail it was two sentences long saying that the bank closed my account due to a low credit score, at the time my credit score was above XXXX according to the three major credit score companies. They destroyed my credit score and sent this debt to multiple debt collectors. I tried after it was sent to debt collection I called them one last time and I asked for a manager a supervisor anyone and each one told me again that it was illegal for them to speak to me about my account, but that they would take a payment from me. I refused to pay because the issue wasnt ever fixed and they refused to speak to me. I am desperate to resolve this issue. I still want to know why they shut down my account and refused to speak to me. I also asked many times for them to investigate how my payment was processed from an entirely different bank then the one I added in the app. But I havent found anyone who could help me with this and my credit score has suffered greatly because of them.