Contract - Data contract

I took out a Data contract contract with Telkom and 24 months ended five months ago. I went to fourway mall where I app**** for the contract and they gave me horrible attitude regarding cancellation of the contract.

Can someone assist me on how to cancel this contract which doesn't benefit me but I feel ****** by Telkom. They are forcing me to continue with them even thou the arrangement was for only 24 months.

I have the same problem with Cell C to cancel my Cell phone contract.