MTN not paying my REFUND

In July 2019 I settled my contract with MTN and continued receiving airtime as my contract had not expired. I was told to call the call center after the 9th of May 2020 to cancel my contract. On the 11th May 2020 I called MTN to cancel the contract and was told that I have about R618 that they should refund me. A refund request was logged same day the 11th May 2020 and I received an sms confirming the refund request with a reference number. I was advised that I would receive my money within 3 to 4 working days. After those days I had not received my money and I called again to find out why, I was told they want proof of payment and I asked why they did not inform me about that, I was told they do not call customers, a customer needs to call and follow up. I sent the POP on Sunday the 17th and was told I would get my money within 3 days... and till today, I have not received my refund. Today is the 11th days since the Refund request was logged. I do not understand why it is that I fully paid the contract but now I am struggling to get what is due to me.

I WANT MY MONEY.