Poor service - clear my name

I regret the day I took a cellphone contract with Telkom, I cancelled my contract after the contract period has ended but the guys at Telkom only cancelled my device contract and left the insurance contract running I don't know why when I specifically requested for all my contracts to be cancelled. I again had to cancel the insurance and pay the fees accumulated but now they can't even provide me with a confirmation letter that the all contracts have been closed and I don't owe telkom anything. When requesting to be sent my latest account statement it shows that I still owe telkom dealing with telkom is so exhausting all they get right is asking you to rate the service even if you give it low ratings they don't follow up to find out why.