Unacceptable service

I am seriously not happy with Nedbank at all. Over the weekend I made an OZOW transaction of R20k from my credit card which was not successful. Minutes later i tried it again and it was successful. Later on the day when i noticed my balance was less R20k than it should be so i immediately assumed it was due to the failed transactions. On my app i saw that there is a failed transaction of R20k which shows a return date of the 24th. When i called the bank to query this on monday the 26th as it was still not credited back, the 1st advisor informed me that the transaction was successful and that i should contact the provider where payment was made to to query this. When i called the provider they happily assisted me and said these errors do happen but asked me to send proof of payments for both transactions so that they can check their records and trace the unsuccessful transaction free of charge if the error was on their side. Then called my bank back the following day and again queried why the amount is still reflecting under my failed transactions and I was not given a reason and the lady told me on her side there are no failed transactions. She then offered to send me a Nedbank dispute form and told me to complete it and said there we T&C's. When I eventually got the form the T&C is a charge of R150. I called my bank yesterday and spent over 40mins with another consultant who kept me on hold until i needed to get into a meeting so i ended the call and no one even bothered calling me back. I was asking for the simplest thing which was the proof of payments for the 2 transactions so that i can refer back to my provider who are willing to assist and check their records free of charge. The strange thing is that i can get proof of payment for the one transaction from the banking app but not the second one and yet the advisor at the bank was able to confirm that the transactions were successful, why can i not get both from my banking app? and why is there an unsuccessful transaction for R20k still there? I am honestly on the verge of closing and moving banks once i get this resolved because if my own bank cannot assist me with transactional information and show no urge to assist me, then i am not valued client and my monthly fees should go elsewhere. I cannot even get the provider to check because they need both the proof of payments so i am in limbo. i am extremely frustrated.