Digital banking victim

Nedbank as my banker is refusing to assist me to proof to another company that I have paid them via the Nedbank Money App. They were able to provide me with some documents to this effect but the other company said it was not enough. Both myself and the other company are clients of Nedbank and the details I used to pay were provided by the Nedbank Money App as a beneficiary to the bank. I believe they have the power and means to provide substantive proof for the payment I made so that I can get my refund as I overpaid the company. I have been struggling to get support from Nedbank and now after tossing my request from one consultant to the other, they are ignoring my emails.