Avis Budget cant do refunds

I will not be using Avis in the future, I hired a car to be collected at king sasha airport on the 17th April 2025. I paid the full rental on the 27 March 2025 and paid a further R4000,00 on collection, I returned the car on the 22 April 2025 and was give a credit invoice of R3500,00. Two emails later with no reply other than they will come back to me soon. As at writing (6 May 2025) still no refund. I have contacted them telephonically only to be advise that they are still waiting for proof of payment. What hogwash you are using my funds for your cash flow !!!!!!!! shame on you - so it's back to Europcar they don't need customer's funds for their cash flow