8ta / Telkom Mobile
How do one cancel an 8ta contract

I phoned 8ta this morning trying to cancel my contract, only to find out that their retention or some department will phone me.
normally if a person want to cancel a contract you write a letter. (for Proof)
the contract is ending on the 1st of may 2013. and it's a few days away, now i have to wait for them to decide when to phone me.
why is this so a hassle to cancel a contract.
i don't have any numbers of them only a call centre and they are not one of the help fullest people.