The pin has already been redeemed

I bought 2 x R100 unipin vouchers at Bargain Buys Eersterust on 18/01/2016. I attempted to redeem the two vouchers on 19/01/2016 and only received the messages that the pin no's have already been redeemed. There is also no call centre or helpdesk no for unipin on the voucher I've purchased. R200 is a lot of money to lose. PLEASE HELP!!!!