MTN empty promise

On the first of July my debit order went off but it was nit correct amount it was more than double I phoned and was told there was a billing problem i had to phone MTN to resolve the issue on Friday 7th I phoned MTN and was told they would pay back the excess amount within 2-3 working days today is the 9th snd still no refund! This resulted that my other debit orders went unpaid!