Incorrect billing

On the 31st of Jan they deducted 3 times the amount they were supposed to as it is a prepaid data bundle contract , when I went into the store they phoned customer services to advise why they deducted so much. They the lodged a dispute , where they said they will phone me with in 24-48 hours , where I'm still waiting for their call to tell me as to why they deducted 3 times the amount and also for the refund as this is unacceptable for them to take more without my consent.