Been trying to sort out a billing query since Aug

I have been trying to sort out a billing query on my MTN account since August 2014. I went into the MTN shop and registered the query with them in Aug/September. They registered the query on the system and indicated that my package cannot be downgraded as requested until the query is resolved. They indicated to me that it would take a couple of weeks to see if the query can be resolved. They never contacted me and I returned to the store to see whether there was any progress on the query. They indicated that there was no response and that they would re-register the query, which they did. I cancelled this contract and took out a new contract with different options. To this day I have not been able to resolve the billing query and I am still being billed for the old contract.