There are a few steps needed to take in order for this to work.. but they will take no longer than 2 minutes.. Here are the steps i took
1) Add 2 copies of Burnout to your basket plus an item of your choice (dosent matter about the price of this item as you only need it to take the total to over £50...I chose Splinter cell for £9.99
2) Go to the checkout and add the code.. you will see that one for the copies of Burnout has gone to £19.99..
3) Continue through the checkout accepting everything until purchase has been made.. IMMEDIATELY go to your "order history" and cancel the order for the copy of burnout at £24.99 and the other item... The total price stays at £19.99 for the other order
4) Sit down and pat your back for being a clever person and saving money
THIS WILL WORK FOR ANY ITEM YOU CHOOSE AS LONG AS THE TOTAL REACHS OVER £50 AND THE QUANTITY OF THE ITEM YOU WANT IS 2 OR MORE