NO SERVICE

I am trying to cancel my telkom landline Tried the internet - only empty promises for a callback, they do not make contact. The e-mail to the address they gave came back as invalid. Tried to reach all three Telkom stores - George, Langeberg Mall and Telkom Mossel Bay - NO contact number works! Being on my cell phone for hours and no joy I need a way to cancel my landline - please HELP!!!