From the original link page, click on promotions, click "add to basket" on all four options. Remember to remove duplicates of the Bike repair bag! (Or click on the individual links and add one of each).
Subtotal will show £39.45
Proceed to checkout, and the total will cut down to £3.61. Boom!
If you try add 2 of each product, it will only do half price. So £78 down to £39.
Make sure you have 5 Products and quantities set to 1