Do you buy a lot in there? I tend to find the more you buy, the more they send you. I base this on being a huge marks and Spencer shopper and I get lots of discounts and offers....and a couple of years ago, I practically stopped buying from there altogether (between jobs, no money, trying to be strong ) and got not a single email/reward/discount from there.
I think the offers are very tailored to what you buy....I buy my fruit and veg there weekly so get a lot of food offers....I'm very partial to the homeware and women's sections so receive offers for there too. I don't buy any mens or kids so never receive anything from those. I have noticed if I buy say jeans, I'll get a "reward" for jeans as my next one....if I buy any homeware, bedding is a bit of my downfall, I do get money almost straight away off more bedding. I'm learning not to try say 3 pairs of jeans on and buy them all as I know if I buy one, I'll get a sparks reward off more jeans. I don't know for sure if it works like this, but it seems to be this way for me! If I have a break from spending there, I almost always get a 10 or 20 per cent off everything reward.
I do regularly get free biscuits/fruit/percy pigs/bread and I'm not going to sniff at that. Anything free is a winner!
I think their advent calendar thing is a bit rubbish. They seem to stop all rewards and I never get anything good on the advent. Nothing going out of my way to pick up. I remember a couple of years ago, a lot of my colleagues even got free vodka, alcohol etc and I got nothing like that!
Edited to say I've just looked at mine
15% off shellfish
20% off throws
10% off fruit and veg
10 % off cleaning and laundry
Free percy pigs
10% off cut flowers and plants
£1 off shopping if £6 spent on sweets.