I just got an amazing deal so thought I would share! I was looking to buy the vitamin E set and it is currently down to £18.30 and decided to buy the vitamin E 30% off deal of the week item too. This cost £25.30 in total.
I then noticed the promos for gifts after spending certain amounts, £23, £25 or £28 so I added an item from the £28 section thinking I would make up the difference but this added at £0.00, I then tried one from the £25 and it added at £0.00, and finally thought I would try the £23 one too and it did the same.
Total after cashback is just £22.26!!!!!! Total order value = £65!
Hope this is good for some people! I think the glitch is if the additional free item makes your order total over the 23/25/28 then you can add it for free! :)