Double charge for services i don't use

I'm highly ****ed off at DSTV, for some reason they just decided re-activate a decoder that I don't use and increase the debit order without me asking or me calling them to do this. then I called to tell them of the problem and they said they will fix it and reimburse me my money back however the next following month they continued to charge the the money for a decoder i don't use and now they keep dropping my calls when i call back