My refund

I canceled my contract with mtn 19 August paid what was due to cancel the contract, end of the month got debited, however my cancelation fee was inclusive of the debit order, now mtn must refund me it is been two weeks now following up on refund got reference number and no refund done yet, am follow up almost everyday and am told it is still on review I mean how long doez it take to review and refund course they can see I even over paid the account all I want is my refund and it shouldn't take this long course I don't owe them all I want is my money