Voucher ****

I , as well as many of my family members received R100 OnlyDayOnly vouchers from Vodacom all with the code VOD-100-PBY. I used mine. My dad asked me to use his using his account. On the 27th he received an email stating the order is cancelled because the voucher can't be used more than once. Firstly this was the first order he placed. Secondly the system allowed the voucher and the payment went through. Why give the same code to all the customers and now cancel their orders claiming the vouchers are not valid.