Unrequested Contract

Few months ago i contacted Telkom to apply for a cellphone contract. I received an SMS that my application was unsuccessful. Days later i got a delivery from Telkom and i called to enquire only to be told i wasn't approved for a handset but for a sim contract. I informed them i wasn't interested and they must cancel. Months later they are still billing me. The package with sim is still sealed, and card was never activated or used. I need them to cancel