Billed for 10 months on cancelled account!

I requested my MTN 3G account to be cancelled once the 24 month contract period had expired. I followed all the steps requested by MTN corporate and sent a signed cancellation form. At the time I still had 2 phone contracts with MTN. Once I had sent the request to cancel I received no further communication and assumed that the 3G contract would be stopped. I did not have itemised billing so for 10 months I just assumed it was my phone bill which was high and that the 3G had in fact been stopped. I never used the 3G once after that point. Once I had stopped both my phone contracts with MTN this year I suddenly noticed I was still being billed R300. I phone MTN and they stopped the contract and promised to pay me back. It has now been 2 months since Gordon Hlongwane from customer service said he would do this and probably about 20 emails to numerous contact people. I have never heard of such a thing where a company cares so little about it's customers that it will not pay back what was never delivered as a service in the first place.