Telkom keeping my line contract to ****** money

I took out a contract with Telkom October 2013, the contract expired October 2015 (24 months) but Telkom refuses to make my line prepaid so they can keep ******ing money from me. Contract is obviously more expensive than prepaid. I have been paying so much money waiting for this line to be disconnected but nothing has happened. They keep telling me its escalated. I am so fed up with this money making scheme, 4 months after contract expires they still don't want to disconnect it.