COMPLAINT ON UNSIGNED CONTRACT WITH DSTV

I was in contract with DSTV that was about to expire in a months time I reported a fault with my dish that was going on and off repeatedly. They sent agents to my house to fix it but they put me on a new contract without my knowledge. When i enquired and complained they apologised but stated clearly that i cannot cancell until 24 months or ill have to pay them the cost of 24 months. This frustrates me as nothing was explained to me on channels and contract over such a long period. They are now deducting my money mercylesslly and say they cannot cancell. I request your intervention and help. Im not a happy customerwith their service