Worst experiance !!!!

Worst experiance !!!!
I have booked the hotel for my guests (family of 4 members) for 2 nights and after the guest checked out the property, later on i got a call from the hotel saying that guest has used minibar and we are going to charge the registerd card for an amount of aed 594, then after 30 minutes they have charged the amount without my confirmation, still i dont know that guests had used the minibar and if yes, why the hotel didnt charge or inform them while they checked out..Strange and unprofessional