Cancel my contract!

I upgraded to fibre in June 2018 and Telkom still hasn't cancelled my previous adsl account! every month I get double charged and I have to phone numerous times to get this disputed. The last time I phoned I was told it would be done by last week Friday. It has not been sorted. Telkom has made it impossible for me to keep them as my internet providers! Someone please help me cancel my previous contract! My cancellation number is 410404.