Poor service and wrongfully charged

In April I called in to request cancellation of my month to month data contract as I was not happy with the service.

The consultant in the cancellations department then apologised and explained what happened. Then carried on to offer me a new contract, which I then took thinking I could give them a second chance. I then asked her to change my banking details for the debit order and she stated that it was done.

Only for them to debit the account I don't use anymore then charge me R200 for the debit order being unsuccessful. Now I have an outstanding fee of R839.40 that has been accumulating for a R59 contract. I have been trying to get a hold of them, even tried using the app to log a dispute but every time I get an error.