Falsely attracting clients

Last year early December I was contacted by this company offering me to upgrade my current dstv subscription, offering me a low price than my current one, I asked them if this will not add to the amount I was paying already,then the lady said no it won't be an extra fees, I even explained to her that I'm on triple view subscription,then she started calculating everything then gave me calculations of lower amount than my current one.

I found out they are on-air TV company after I received sms approving my purchase, the lady never mentioned that they are onair TV once during our conversation, I thought I was talking to a Multichoice consultant because I have account with them.

On the 8 December I received their decoder, after I contacted them immediately via email to cancel their subscription,I even told them that I did not open their package they can come and collect it,because I also realized that I would have to pay extra,which I can't afford.

On my pay day they debited I reversed it coz I can't pay something that I'm not using, the package is still sealed i told them they can come and collect it,now they called me and says 30days is over I have to pay something that is not even activated how??

Please help me,I think this Company falsely make us join them pretending to be a Multichoice Company, after I realized who they are it's already late because the purchase has been made and if I try to cancel they are asking for cancelation fees ,that's not fair because during our first conversation the lady never mentioned Onair TV, because if she did I wouldn't gone any further.