Theft suspicious

My son loaded his bus card on 29th of August 2022,was Friday, they gave him a slip with a balance written with hand instead of computer printed, he loaded the amount of R150, then the balance they wrote down shows R168, today he couldn't go to school as the card shows insufficient balance (01/09/2022 Thursday) how possible is that? Why they are lazy to print a balance slip for us as I'm using the same transportation, but my card is still alright. He tried to get help but no one was interested, he had to written back home, a school child! No someone must do something about it.