Misleading Vouchers

Still my favourite clothing store because of the quality and size cut. BUT, they are so misleading, so if you purchase for more than R1500 they offer you a 10% voucher, now here is were there is a catch, this voucher is valid for like 14 days, minimum purchase is R1500. Why are their vouchers only valid for a few days, there is no way that after buying for 2000 you will buy again for another R1500 in the same month. Consumer protection should look into such misleading vouchers. In my opinion, it should be valid for 3 months atleast, or better off never expire.