UCT Refusing to Refund me

On the 26th May 202, I paid an amount of R370 for NBT using FNB Bill payment. The transaction amount was deducted twice, I have been trying to get my refund from UCT with no luck. I have sent my transaction history reflecting the amounts but they say it's not sufficient, they want proof of payment. However, there is no PoP when paying a bill via the FNB App, other than the bank statement and the transaction History I have sent and was told its insufficient. Can UCT give me back my money please?