Bad Customer Service and withholding refund

I rented an i20 Hyundai on the 18th to the 20th September 2020. I have been querying my refund till now and they advised that the refund would be processed in 6 weeks. The branch Supervisor Lauren Mansvelt at the branch in East London has not been giving the run around claiming the funds have been transferred in my bank account. What upsets me is that Mandu Lichechane the Customer Care Administrator does not answer my calls when I want clarity on this matter. I am sick and tired of this nonsense this company has no proper procedures and standards, they have bad customer service. And most people I have interacted with about this matter say that Avis makes it a habit of not Refunding people their money, i am not the first one. They are failing to send proof that they have refunded the funds from their bank into my bank account, instead they sent me a TAX INVOICE which proves nothing. I have been going into the bank to check if the funds were refunded and they are lying to me and making me a fool. I WANT MY MONEY BACK from AVIS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!