Found 8th Aug 2016
Loads of vouchers in a pile behind counter in Glasgow sauchiehall st. Guessing they're in all branches and if you're confident you could just ask for one to buy your drink with. They're valid until Sunday 14th. I just grabbed one from till area. Only valid 2-6 everyday. I think you're meant buy a medium hot drink to then be given this voucher for half price cold drink. But she just let me have large cold one half price yay.