Payment to cancelled contract

Good day, My wife had a dual sim phone and 2 contracts (voice & data). She cancelled the data contract a month before it expired in March. The voice contract was changed to a R39/month option. Cell C didn't cancel the contract though and kept debiting her account. Every month since the instruction her debit order was rejected due to insufficient funds which added another R80 to the account. The Cell C employees at the branches are obviously not customer service as they are not allowed to do anything regarding contracts unless it is a new sale. Not at all possible to discuss a situation face to face. Every time she had to call the customer service number, hold for more than 30 minutes only for someone not to understand what her problem is then get transferred to a manager who promises to get everything sorted out. by the end of the month she would get another message of insufficient funds with an added R80 to the money due. Efforts to get a refund were fruitless and 2 days ago after struggling with reception realised her current voice contract (supposed to be the continuation on R39/m) was now cancelled. This put us in a very vulnerable position in case of emergency. Best option is to port to another service provider, but no-one can tell if the sim is cancelled with possible penalty for cancellation, or just blocked? The customer service also refuse to talk to me, they only want to talk to my wife. There just doesn't seem to be anyone who can assist with cer*****y that the issue is resolved