Unable to cancel contract

Please help I have a contract with OnAir which I joined last month March and the contract was not explained properly that it doesn’t have DSTV channels. I did not use decoder until I know how it works and then I called OnAir to check on how the decoder works and they told me that it definitely doesn’t have channels and I requested cancellation immediately and my first call with them was 4 April 2025 and they keep promising that an agent will be in contact with me. Up to now I still don’t have any contact from them to do cancellation