vodacom- Disappearing air time bought at a super market

On the 25.08.21, I went to the local spar wilropark Roodepoort to buy airtime of R29 for cell *** at 14.32. Arriving home 10 min later I tried to recharge using pin *** as provided on voucher.To my surprise the message was voucher pin invalid. Tried several times at that time and nothing.The next day went to vodacon shop and they said nothing wrong with phone .went back to spar and they called vodacom.was toldthey had problems on the 25 the and that the voucher was used for another phone that evening around 8 pm.impossible as I still got the slip with me and no one was in the house. Surely they can check when I tried to recharge and the decline messages.Or do they sell duplicate voucher's?