I got a Redbull voucher from SHELL drivers club for half off a can of Redbull 355ml can. In the shop they were doing 2 cans for £3 so I got 2 cans to see if my voucher would work on top of the 2 for £3 deal and it did. I only paid £1.95 for 2 big cans of Redbull.. Do join the Drivers club they randomly send you emails for extra bonus points and you just click a button and get 200 points for filling up atleast £15 or £30 depends on the deal. I also got a £4 off voucher for fuel. So I am a happy camper.