A bit of trickery going on here for this price, but at £18.00 a box, I think it is worth of for their best flavour ever.
Follow the steps below:
1) Go to the grenade website and sign up for the newsletter (add a full stop in your email address somewhere random of you've signed up before) for a 20% off code.
2) Once you've got the code, go to the Grenade website and choose a two box bundle of 2x Oreo bars and add them to the basket. (Important! You MUST choose the two box bundle for this to work).
3) You should get a pop-up (like seen in the images above) of a promo to add a box of Oreo bars to your basket for £20. Accept it.
4) Navigate on the website to find a single box of Oreo bars for £25 and add that to your basket.
5) You should now have 3 items in your basket: 2x12 Oreos bars@£45, 1x12 Oreo bars@£20, 1x12 Oreo bars @£25. Remove the 2x12 @£45
6) Apply the 20% code and pay!