Trying to cancel service. Can't get any confirmation

I don't live anywhere near a Telkom branch. You were supposed to have my line up at new place by 1st December, which was not done. You've billed me (plus some) for the full December and I've been trying to cancel my services with you as you have not been able to install a line and I won't be using your services any longer.

As you are aware, it is impossible to get hold of you telephonically. Because I live far out of town I was given an email address of an employee during the follow-up of the non-installation (which I was told I wouldn't be billed for, which I have). I can still not get hold of anyone.

I would like to cancel my services effective immediately and I'd appreciate you looking into billing me when you were not able to fulfil the service promised.