When you do manage to give the freebie vouchers to people, you don't think about the long term consequences of this action. Until they come back in the next week laden with items and waving the bit of paper in your face. "Hi, I've got this coupon someone gave me last week and I'd like to redeem it please!" Cue half an hour of you explaining that they need a special number of books to use the voucher, by a particular author, with a particular coloured sticker on - oh, and actually their voucher expired the day before. You're so tired of being yelled at for no reason; you can't help it that the CEO of WH Smith came up with this ridiculous way of drawing in more customers. They should just offer cheap chocolate or something (hang on, that's not working either...)