Onair ****

I haven't used the onair device and I would like to cancel my subscription, they're saying its not possible because I agreed for 24 months...excuse me but I was told I can cancel it anytime...which is ridiculous...why does it always have to be cat and mouse with these people? I was told this was upgrade from my normal Dstv channels as the decoder i was using was old...not anything about a 24 months contract...I want to Cancel this **** immediately...the consultant from the call center i rude and are unable to help...