Unable to cancel ADSL Line and Internet Contract

I have been trying to cancel my ADSL Line and Internet contract since the 17th of May. I went to the the Telkom store in the Hemmingways mall and was advised that I must cancel my contract online. When I tried to cancel my contract online, all the services remained greyed out. I contacted 10231 on several occasions only to wait more than 45 minutes for my calls to be answered. When I eventually reached an agent, Tebogo, he advised that I have an amount owing for the month and therefore would not be able to cancel online. He would send me a cancellation form to complete. I have still not received it and I'm unable to contact the 10231 number as I am now living overseas. Please urgently assist. I am not willing to pay for services after the sale of my house on 19 June 2018.