ok i only saw a banner for it while i was on my way out so i'm unsure of all the terms and conditions, but it basically said when you spend more than £25 on groceries in store you will be able to get a £25 discount on a tesco mobile phone worth £50 or more.
it said it expired in january, and i think it said the 28th but i can't be sure, either way you would have all of december.
you could view this as when buy a tesco mobile phone worth £50 or more, you get £25 of shopping free...or something.
my first deal, sorry if it's in the wrong section or anything. be as mean as you like, i won't cry...