Dishonest Onair TV

On Air TV called me realising I don't know how that I am using an Old decoder. they told me that they are doing a promotion for two DST Explorer and monthly payment will be R160. I indicated that I do not have money but what interested me was that I will own the decoders after 6month since they a doing promotion. I accepted the deal. After 6month they told me I have to pay for 24 month period, I disputed that and I requested a transcript since we agreed on the phone. they said they do not have the transcript or recording of the conversation with them. There was an error with the recording. I spoke with one of their consultant Merlyn Oakes (Ref No: ***). We agreed for them to come and uninstall the devices and install my old device. I have her emails on record. till today they still have not come. They still want me to pay something we did not agree with. I do the reversal of payment and they are threatening me with legal action. For me to continue to pay I need a recording or a transcript as evidence that we were in agreement of 24 months period. thanks