Bad service

I have been trying to contact MTN since yesterday to cancel 2 of my contracts, I eventually emailed them. They are only busy with 1, they send me an email to say they tried to contact me but I did not answer. I changed my main number on numerous occasions but they are still using a number that is not the main number anymore and not on my person everyday. Today I was told to phone them. I have been phoning and holding the lines for more than 30 minutes on each occasion with no answer. Now the contracts are going to a month to month which I am not interested in.