We all know about 'Raincheck' vouchers from Tesco (and elsewhere) where you ask at Customer services for a voucher to use next time if an item on offer has sold out. I took this a step further today in Tesco with the Ben & Jerry's 2 for £3 deal. I stocked the freezer up as they had a good stock available, but one of the flavours was sold out. I made a note of that flavour and picked up a voucher on my way out. So in a few weeks time when I need to stock up again I can still get the same deal even though it'll be long finished. Simples!