Refund Delays, No Accountability!

Below is email was sent on the 01 June 2021 and to date no response has been received:

I would like to get some clarity on what is the letter of authorisation as my application was rejected because of it. I submitted the bank confirmation letter, bank statement showing payment and affidavit from the person who paid but still got rejected. I also tried looking for documentation of authorisation on the university website of refunds in case it needs to be filled in but found nothing.