Contract cancellation request via email not action

Twice via email to Tshepiso I requested for my contract to be cancelled(email dated 18 December 2014 and 19 January 2015).. first my debit order was cancelled by MTN and then I had to do EFT and mail every time to reconnect my service.. when my contract was done.. I stop using the number as for some other person keep on giving up my number for his accounts.... Now I get an email that I have been handed over to VVM Debt Collecters... and when you call them they tell some one from who is handling MTN's accounts will call you back this is now 2 weeks later and nobody is calling back.. they insist I must pay R2743.79 or they going to instate a order against my salary... who's mistake is this... as for the consultant I email due to the 808 not answer or handle cancellations at that stage... I as a customer did request a cancellation in time... and it was never cancelled.. so it seems MTN wants to make money out of us