ShopRite can't tell me who has used all the money on my voucher card

I have just had the safest story on a Sunday. My colleague was saving money in a form of vouchers with shopRite in order to buy groceries. She managed to save a thousand rands on the card on Friday she went shopping and when she paid the lady at the till was rude and told her that she could not make any purchase because her funds were insufficient. This was troubling for her because she needed to buy her groceries. The most annoying matter was that she was told nothing could be done because the purchases could not be traced,of which I find very desturbing and I don't want to believe that it is the truth especially for a brand as big as ShopRite. One can just emagine the amount of transactions that happen at ShopRite daily. It's sad how people who are not properly trained can make a company loose a lot of clients. We can't afford groceries,clothes and still buy stationery at onset that is why we pay vouchers during the year. Her Name is Jeanette kgole, her numbers are *** please guys it's the festive season .I hope that the shop redeems themselves.