This is theft

On Thursday the 26th of March my sister tried to withdraw money from her student allowance card at Shoprite in Berea center. the cashier told her R1000 withdrawal was unsuccessful only to find out the money came out of her account. We then went to the store on Saturday the admin manager Reina Swart who had little care and time when told of the incident she told us she needs an account statement so they can see the money did come out. mind you this was after some of the staff had told us that the store was a R1000 on that very same day and the cashier admits she remembers the transaction. The statement was sent to her. the whole day today we've been calling and the answers we've been getting just don't make sense. she no claims the R1000 that was over on the Thursday belonged to someone else and my sisters R1000 isnt reflecting in their account.