Very bad service after sale

I had received a very bad service after the sale... I initially rejected their offer and the guy kept on being persistent by explaining the benefits of the router and sim. I agreed even though Im still having onother router on contact that I'm still paying. Now after so much sacrifice that I have made they are unable to help with the issue that I have.... Just received the router yesterday and the router is not well functioning....still withing the cool of but now I'm being advised to go to mtn store to obtain what ever they said I should obtain in order for them to help with the contract cancelation.... I future pls dont phone me with your promotions or whatever offer you might have on promotion.. I'm OK with your service. I'll phone you back tomorrow with the number that you asked for and cancel this contract.