Huge delay in refunding me

I am appalled by MTN and their lack or urgency in concluding my matter. I moved my contract to prepaid at the start of the year yet after the waiting period they still continued to debit my account as if I am a contract client. I contacted them and they apologized saying the matter will be escalated at resolved. This was in April already. It is at The end of May and I have still not received my refund. A Different representative Keeps contacting me to say that the matter was escalated and will be resolved but I am still waiting. I have 2 reference numbers of my matter #*** and #***