Cannot Cancel business account

After 2 years of being on this dismal network, my contract is up for cancellation. I have tried to cancel it by emailing them, i have tried the call centre, the website and even going into a Cell C shop. Nobody seems to know how to cancel a business contract!! Business connects me to retentions, who send me back to business. Is this a deliberate delay? I am at my wits end with Cell C. Your network and customer service are pathetic!!