I just traded in £15 of Tesco clubcard vouchers for £30 of pet food vouchers to spend on any pet food in store. They email the voucher to you so you instantly double the value of the clubcard vouchers. Awesome deal
I got really pissed off with this last time they did it. Went to buy some flowers for someones birthday so exchanged £5 for a £10 flowers voucher, but youve got to spend the full amount of the voucher and of course there are loads of flowers at £9.99 I wanted but none for just over that. Ended up having to buy some dirt cheap ones to make up the 1p and just throwing them away.