MTN cancel the contract

I bought mtn home router online and I asked the person who assisted me if there is coverage where I stay and she said yes as I gave her my home address, only for her to use Sandton address just to push her sales, got the router the following day, it never worked it was on Friday, it worked Saturday for 1 hour after that it ddnt , I then called MTN and they said I should return it to the nearest MTN store I did that and got a reference number, was told to call again for final cancellation I did that, spend over an hour with the authentication only for the person to tell me that the can’t help me and gave me a number to call ***** that number goes though but it’s never answered, it’s been a week without help and I can’t pay for something am not using , kindly help, even contacted them via facebook inbox but no help , why is it so difficult to cancel but it was easy for them to sell to me, it just shows they don’t care about customers but only money