Vodacom is refusing to refund me

I app**** for a premature cancellation, received the quotation and paid the quoted amount. After being advised by the retentions department, I cancelled the premature cancellation. My Vodacom account was credited and my upcoming invoices would be debited from the credit I had. However Vodacom debited my credited account with the premature cancellation plus the fee for the full contract. This happened at the end of August and I raised a query about it with Vodacom. Sadly Vodacom still has not rectified the issue and I’m still being charged the full contract amount even though the premature cancellation was debited. The accounts department throws the blame on the retentions department and vise versus. I’m extremely disappointed with Vodacom and will no longer extend my contract with them.