Product: Credit card or prepaid card

I recently contacted Discover Card XXXX on XX/XX/2022 to inquire why my interest rate was increased. Requested a lower rate on my account. The representative informed me that this was not possible since the account is closed. This option is only available on future purchases. I asked why I am paying interest on a higher amount that the balance I owe? The representative told me that the bank charges an average daily balance and that I am at a variable rate and the prime went up/ Incidentally this is Discovers standard answer. 
Last year I contacted the Federal Trade Commission about businesss practices of this bank. I detailed the bank interest charges on a much higher balance, and informed the FTC of the interest charges on the original balance instead of the current balance owed at the time.. I have been paying discover close to $ 600 monthly to reduce this balance. However, the interest seems to rise as I attempt to bring the balance lower. The issue began when Discover arbitrarily raised my credit limit without notification and between the increased interest rates without warning I suddenly had an enormous credit card bill that was next to impossible to pay down. I have come to learn from dozens of people who experienced the same situation with Discover bank. In addition, I have paid over {$9000.00} over the last three years and yet this balance seems to take forever to pay down. The interest rate takes a substantial portion of my payment. Also, my card payments are never reported to any of the national credit reporting agencies. However, these agencies have the balance I owed, which causes my credit score to significantly decrease. This in turn effects my credit score and raises my interest rate with the bank. They do not report my payments or lower balances to keep me at a high interest rate. I find this to be the worst deceptive banking practices. I am hoping that CFPB can look further into this matter since so many consumers are struggling with the current economic climate. I have faithfully paid my bills over the years and in fact was a loyal card holder before this situation occurred. I closed the account when I attempted to get more information on in the past charges and questioned why I had repeated charges of similar amounts on my card. The balance seemed to escalate in a brief period. This was around when Discover notified me about the XXXX XXXX XXXX and my card was part of the situation, so they changed the number on my card. Incidentally, the credit card number was changed by Discover more than once. 
The representative I spoke to at the time was very uncooperative. At times he was rude and stone - walled my questions and requests. I called again looking to resolve the matter with another representative I could not get anywhere. I closed the account even though I did not really want to. I had this account for several years, but felt closing was necessary to safeguard the account. As a result, closing the account impacted my credit rating as well. I would like the interest lowered so that I can get the balance paid down to zero in a timely manner. I would like to request that Discover Cards banking practices investigated further. I have spoken to others who have had similar experiences with Discover Card ; they are just as frustrated as I am. Thank you for your assistance in this matter