Telkom Wifi not for Delft

I have taken out a contract for Wifi with Telkom with the promise that it is conducive in my area (Delft) only to find out that we more off /no network than anything else. Telkom expect me to pay the contract in full and this for a service they could not provide. Now they still deducting their instalment and I am pulling my hair as I have taken out rain wifi. What can I do to get this contract stopped at no cost please ***)