MTN a big disgust

In 2013 I have upgraded my one contract and took out 2 new contracts. The one contract was used for a business phone. However, at some stage my business collapsed and I wanted to do a migration. I was unable to perform a migration as the accumulated airtime would be lost of about R8000. In December 2014 I received a letter from MBD attorneys stating that I owned MTN money and made payment agreements with them. A payment of R9600 was made in January 2015 where it was promised that my MTN account would be re-activated. I have struggled to get through to Customer services and when I get through, I am transferred to the collections department. I have not received any valid response from MTN as to why my contract was handed over initially and since the payment of R9600 was made, I am still forced to pay for a service that I cant use, have R8000 worth of airtime and cannot be refunded for any airtime that is already paid up, by now it should almost be R20 000 and I am changed for connection services every month. And to top it up, MTN is offering me the chance to upgrade me 3 non-existent contracts.