It's my money i want it back or at least want to know when i'll receive it. NOT THIS UNRESPONSIVENESS

My MTN account handed over to MBD Attorneys, I then made an arrangement, setup a payment plan on my online banking profile and started paying MBD. I then decided to settle the account early and first week of September 2018 I call MDB and ask for settlement amount and pay it in full, a week later I receive a paid up letter. Due to my payment plan I overpaid the account by a R 1 000.00, 2 weeks after having settled the account. According to MBD I overpaid by R 700.00. This happened on the 20th September 2018 its almost a month and I still don't have my money back. MDB says they waiting on MTN as the money is paid directly into MTN's account. and MTN hasn't responded yet. when calling MTN they says I need to deal with MBD as they sold my debt. All I want is my money back. MTN & MBD Attorneys PLEASE PAY BACK THE MONEY. Now when I call they unhelpful, don’t have proper answers and irritated by me.