Faulty decoder

I went to a service centre for DSTV this past Saturday to fix the decoder as I never used it as it stays on channel 100. I called the Call Centre, sent a message to the Whattsapp helpline and I then decided to go DSTV as it could be the decoder. I went to the one at Maponya Mall I was turned away due to the fact that there were too many people. My complaint is I have been trying since March to resolve this and despite the fact that I have not used my decoder I have been making payments. Please help me I just want the decoder fixed. Sandra ***