Unexplained debit order

This is the second occassion where Telkom Mobi has deducted money from my bank account in error. When trying to contact them to follow up on the issue they advise that they still investigating. I was patient the first time this happened but in the second instance the value that was deducted was more than ten times the initial deduction. this is unfortunatly unacceptable and a huge inconvienience as now i do not have access to MY money until they are done with the investigation.