Complain about dstv installation that did not take place

I bought a dstv explora plus on the 2nd of February and I was told the the installation will happen within 5 to 7 working days. The days passed i made follow ups and I was always told they will investigate and come back to me but that never happened.

Its over a month now and nothing happened, so on the 15 of March I contacted them to tell them I am cancelling the contract and they said they will try to investigate and return the dish first and they will come back to me. I haven't heard anything from them and is stressing me out because they are debiting the money.