Impossible to Cancel Contract

My Telkom Mobile contract reached it's 24 month cycle last November. I requested for the contract to be cancelled and moved to pre-paid. The retentions department contacted me and I told them I need the contract cancelled. Since then the contract has not been cancelled. I've been to the Cresta branch 4 times and they say they cant cancel the contract, the cancellations department can only do it. They said I must call 180 to follow up. When I call that number they say that they cannot cancel the contract as they not cancellations. I request cancellations contact number and they apparently don't have a cancellation number. Whose going to refund me my premium over the last 3 months!!!! Case No. ***2