Unable to cancel my decoder

I am extremely frustrated with OnAir. I bought a decoder which was delivered in December 2018, but I decided to cancel the order. I phoned in January 2019 to cancel my order. According to the agent, the systems were offline and no-one could help me. In March, I once again phoned OnAir, requesting to cancel my order. Nothing ever since happened. I phoned in June, July, August, September, October, with no response. It is confirmed by your office that the decoder was never installed. I even cancelled my DSTV in February 2019. Every time an agent confirms that a courier will be sent to my home address, but up until now, nothing happened.

And of course, my account is now handed over to MBD, still requesting me to pay the outstanding amount. I refuse to pay anything for the decoder. Please come and collect the decoder that is never used and still sealed in its original packaging.