Customer Service - NONEXISTENT!

I've been trying for months to convert an expired contract into a pre-paid account. Getting through to the correct department is nearly impossible, and when I did get through I supposably failed the security questions. To add insult to injury I get weekly calls from Cell C telling me my contract has expired and can they upgrade me (not would I like to upgrade)! But what does irritate me is a call from 084 135 that when answered, puts you on hold! STOP phoning me, and change the number to pre-paid!!!!!