Hard time cancelling contracts with telkom

My husband has been a loyal customer to Telkom, he has taken over 6 contracts with them and made sure payment was done, however we called the call centre to cancel a laptop contract, it took us some time to get this cancellation done as the store and call centre were of no help, the agent cancelled the wrong contract and we were expected to pay a fee to unblock the contract she cancelled, we did mention that it was the agent's fault as she did the wrong thing, all we heard was we need to pay an amount to unblock the contract and they can't do anything about that, once paid they sent a bill which was higher than normal, when queried about the lady at the store was very rude and said she can't help and it's not her fault my husband didn't have money in his account which was totally uncalled for as we wait for the payment to go out, Telkom keeps harassing my husband with legal notices but when we asked them to investigate what the agent did they haven't phoned or emailed us with any feedback.we made it clear that we will not pay anything until we get answers