Cell C - Holding me hostage, won't let me cancel contract even though expired!

Trying to cancel a contract that has expired with Cell C and the service has been atrocious, The call centre takes ages to get into and when they do attend to you, they take 5 minutes to capture all your details, then warn you that you will be sent to another department, and the call may cut, guess what it does! Next I tried to e-mail them on their customer services automated e-mail system, they responded with an automated e-mail with an incident number: [Incident: 190 ********** 27] Apparently they take 24-48 hours to respond, That turned out to be false as well, it's almost a week later with no response or reply!