Appaling Failure to refund Buyout fees!!!

We moved our corporate cellphone contracts from Nashua Mobile to MTN, part of that transfer was that MTN will refund us the Termination fees / buyout fees that we incurred at Nashua Mobile during this process. This process was initiated in Aug/Sep 2013. We have been trying effortlessly to get the buyout fees from MTN , and most recently dealt with Collin Kunene who is the Senior Sales Manager at MTN. Our agreement was that they would pay us the termination fees or credit our account. To this day, they still haven't paid even though we have it on email that the funds would be paid since last year. we filled in vendor documents and where told over and over that this matter will be finalised and its still not finalised. As a result, we have had our lines disconnected countless times due to this, and all my emails are going unanswered, he doesn't pick up any of my calls, he is flat out ignoring me. Our company took a lot of lines with MTN and we have had appalling service especially from senior management like Collin Kunene!