Product: Credit card or prepaid card

On XX/XX/2020 I went to make an online payment for my credit card at Discover. I had put {$150.00} to cover the late fee I owed, the monthly fee I owed, and a little bit extra so that my account wouldn't go into the negatives. Later that day I had chatted with an agent about the status of my payment because it was pending, and I had never had a payment pending before. The agent went on to inform me that my payment hadn't gone through and that I should be more than happy to place a new payment for myself. I said I would like that very much, she let me know the payment went through and I should see a statement for {$150.00} on my account in a couple minutes. A few hours had passed by and it still said it was pending, and my bank account still had the {$150.00} sitting there with no pending transactions. I called to check on the status of my payment again and a new agent let me know that the payment would go through at the end of the day around midnight, and not to worry. I asked her if it was just one payment because I had made two payments thus far, but let her know one of them had failed. She let me know that the one that failed would not be going through, and that only one payment of {$150.00} would be going into my Discover account. The next day I checked my Discover account to see if the payment went through and saw that {$300.00} was paid off and my Discover account went from {$530.00} to {$300.00}. I knew this was wrong because the account should've read {$380.00}, then I looked at my recent activity tab and saw that there were two payments of {$150.00} totaling a payment made of {$300.00}. I had assumed that this was a technical error on behalf of the Discover app, and that within a couple days it would correct itself and show it was only one payment of {$150.00}. I had continued to make a couple purchases on my account, but made sure I didn't go over {$150.00}, by the end of the month I had spent a total of {$78.00}. When I looked at my statement it showed that I went into the negatives and my account read {$530.00} with and available credit of - {$37.00}, when at the beginning of my XXXX payment it had said available credit of {$150.00}. With these numbers, that means I should've still had an available credit of {$79.00}, but I was in the negatives. That means {$110.00} just went missing because it is nowhere on my recent activity, there was no overdraft fee for that amount, there was no return fee for that amount, and there was no other spendings I made apart from the {$79.00}. I logged onto Discover yesterday to make my minimum payment of {$35.00}, and when I went to do so it let me know that my debit routing number was removed off my Discover account, and that I would have to fill it out again. I filled it out, everything was correct, and then it told me that the routing number could not be connected to my Discover account at the time and to contact my financial provider. I then called my bank, XX/XX/XXXX, to ask if there was any reason why my routing number wouldn't be able to connect to my Discover account, and they let me know that there was nothing that would restrict that. While I was on the call I asked what XX/XX/XXXX return fee policy was, and it is no more than {$30.00}. Once I got in contact with a Discover agent I let them know that I was having troubles placing my debit card onto their website to make my minimum payment for that month, and after a few ridiculous questions they finally told me it was because I made a return fee. That's why my routing number could not be linked to Discover. I then called XXXX back to see when the return fee was place on my account, and why I didn't see in my transactions on the app, that's when they informed me that there was never a second payment made through my XX/XX/XXXX account so there was no way there could have even been a return payment of {$150.00}. After getting off the phone with XX/XX/XXXX I contacted Discover once more asking why there was missing money from my account and they continued to insist that I must've done something with that money orXX/XX/XXXX. Anytime I would start saying the words " lied '', " fraud '', or " unappreciated '' they would send me to another agent and I would have to start the conversation all over again. I have screenshots of some of the conversations I had with the agents if the CFPB needs more evidence of what was going on. Even after I insisted that the missing money from my account was not a fee charge, they just kept telling me there was nothing that they could do about the money. I was very frustrated, none of my questions were getting answered, I kept getting blamed by Discover, and I still have no idea where my money went from my Discover account. I just want answers, and I feel like I am being played for a fool by this company. I don't have any way to add my routing number to the account to pay my minimum payment of {$35.00} this month, and that is due on XX/XX/XXXX. I just want to get to the bottom of all this, and I want to know why money mysteriously disappeared from my Discover account and I am back in the negatives even though I shouldn't be. In the last two screenshots I attached it shows how there is only one charge of {$150.00} on my account and now second charge or return charge.