Nobody Home

I have been trying to cancel my contracts with a two months notice period. I went to a Vodacom store, they told me to phone ***. I phoned the number. After 22 minutes - nobody had answered - I kept listening to the music and an automated voice now and then. I then phoned back, but entered the Upgrade option instead of Cancellation option and my call was answered in 2 seconds! I told them I wanted to cancel - they again put me through to the extension that nobody answered. My guess is that they don't bother to answer for the cancellations option - but if you want to upgrade - they are there for you in 2 seconds. I tried this a few times - both times upgrades answered immediately. I have yet to get through to cancellations. HOW DO I CANCEL MY CONTRACTS? I will not be liable to continue this contract BECAUSE I cant get through to anybody to cancel it and I cant keep holding on for over 20 minutes as my phone is going to go flat and I need it.