Product: Credit card or prepaid card

I made a payment through bill pay, electronically from my XXXX Bank account on XX/XX/XXXX in the amount of {$100.00}. to Capital One. The payment was supposed to be paying off my XXXX XXXX XXXX account that Capital one took over because Lord and Taylor closed. I mistakenly sent this one payment on XX/XX/XXXX for {$100.00} through Bill Pay to an old closed account with Capital One. I realized this when I looked at my statement and noticed I never received credit for that amount and then I also realized that if they had received that payment I had paid too much and they owed me {$35.00}. So after contacting Capital One and explaining this to them they gave me a credit adjustment of {$100.00} and asked me to provide a copy of the electronic transfer report from my bank. I send them a copy of the confirmation page and number and a copy of my statement, showing the transaction. Capital One said that was not good enough and that needed to have the Bank said something. So XXXX Bank send them proof of payment I would say at least 3 or 4 times and they are still not satisfied. I even had a supervisor at Capital One contact XXXX Bank and walk them through exactly what they require and Capital one is still saying it's not enough. The Capital One Credit division supervisor can not talk to the area where all this paperwork is being sent so all they keep on saying is that it's not enough. XXXX Bank said they have sent everything they possibly can send proving that this was paid to Capital one and there is nothing more they can do on their part, especially because this payment was sent electronically. Now, this has been going on since XX/XX/XXXX. I have spent hours on the phone and many months of pure frustration to the point where I said I can not allow this to affect me this much and decided to let me deal with this at another time. So after the last letter from Capital one DATED XX/XX/XXXX said ( because we didn't receive the documents they requested the credit adjust they gave me for {$100.00} would be put back on my account. ) I went and paid the balance of {$68.00}, through bill pay, to the correct account number, and this time it went out by check. According to XXXX, the check was sent on XX/XX/XXXX and they should receive it no later than XX/XX/XXXX. Guess what, would you believe that I received a late notice from XXXX XXXX XXXX via email yesterday XX/XX/XXXX, that they never received payment and they charged me a {$29.00} late fee!. So now here I am again today on the phone with a Capital One Supervisor explaining what had occurred and their hands are tied so all she could do was credit me back the late fee and had me pay this again over the phone. I then had to call my bank and request that they waive the stop check fee, after explaining to them this nightmare that I am having with Capital one. They did and I hope and pray that the stop payment works. 
I have now made 2 payments of XXXX, only one should go through, and {$100.00} on XX/XX/XXXX. They owe me {$100.00}. 

I am beyond frustrated and feel like my hands are tied behind my back I can not believe this is happening and I feel like there is something going on in the Credit card area of Capital One, especially now that my check that was sent out electronically to the correct address on XX/XX/XXXX and it was never received. 

I need your help, I don't know what else to do. Please help me resolve this. Thank you