Product: Credit card or prepaid card

On XX/XX/2023, I saw on my credit report there was a {$19.00} amount showing for the Capital One Walmart credit card that I had closed in XXXX. I signed into what I thought was a closed and done account to see there was an interest charge that was posted on the XXXXXXXX XXXX XXXXXXXX for {$19.00}. Also, another charge was posted for a late fee from XXXX XXXX for {$19.00}. I thought and was told my account was paid in full when I called to close the account on XX/XX/XXXX. I asked for a final statement too be mailed to me, which I received. I was sent the XXXX bill with the amount I had paid to pay off the card. In the letter it gave 4 different reasons, one being that my account had been closed and had a XXXX balance! The other three reasons couldn't be applied to the letter. 
I understand residual interest, however, how was I know there would be any charges when I had been told the account was closed and I had a XXXX balance? Your policy on this is extremely deceptive. Had I not seen the amount on a credit report, the charges, and late fees would have continued on and on. Myself having XXXX knowledge because I had requested the card be closed after having paid what I was told was the final amount, and my account had a XXXX balance! Again, this wasn't only by phone but your company verified it by mail. 
I first spoke to a customer service rep who was of no help so I requested to speak to a supervisor. XXXX came on the line and like a robot answered everything I said with the same answer as if he was reading it from a card. I asked for the charges to be removed from my account and was told no. I then asked to remove the late fee, which he did. He then asked which account I wanted the payment taken from and I told him and he said ok, I said goodbye and so did he. A short time later, when checking my accounts there was no payment listed. I called back and ask for a supervisor, this time getting XXXX who spoke to me like a human being. However, after telling her, she says she sees that I was given a credit for the late fee but there was NO RECORD of me having just called an hour before! Though she tried to be helpful all she did was give me a confirmation number for the debit of my bank account for {$38.00}. Yes, even though I was given credit for the late fee, I still had to pay the full amount. The credit wouldnt apply for 3-5 days. When I continued to ask for the date of the next time Id be hit with interest charges or was that all, XXXX said she had know way of knowing! Well if she has no way of knowing, how am I to know other then have to check several times a day every single day as now I live in fear of missing a payment of something that Capital One said I had a XXXX BALANCE on. 
This shouldnt be happening, I was told by XXXX and XXXX that there was no way they could remove the interest charges. Thats a lie, on the back of there own statement it says they can if THEY WANT to. I had never once missed a single payment, not once. However when you did hit me with that interest charge my rate jumped from 29.99 % to 31.99 %! Is that even legal to do? If so, that isnt right, this is why people are in trouble with credit cards and file bankruptcy! As if 29.99 % was so far above the average XXXX amount of interest to start with.