Can't cancel Telkom contract

I am struggling for over a year to cancel a data contract. The shop in Tygermall "cancelled" it via email. It is still active. Now I have to cancel my 2nd LTE contract and downgrade my cellphone contract. You can not cancel it. The cancellation email adres is useless! The telkom website show this easy way of cancelling your contract. You can not cancel a contract online!