I am aware that the BUY 3 GET 4TH FREE facility on this listing will not work for you automatically at checkout. Unfortunately I can't fix this. Instead please do the following:
1 - add a message at checkout stating 'BUY 3 GET 4TH FREE PLEASE' (this will confirm to me that you have read this), then;
2 - just pay whatever it is asking for at checkout and then when I go though sales at the end of each day I will refund you for what you have overspent. Please be patient - this won't happen immediately but it will happen.
To be clear the discount applies to the cheapest of each lot of 4 minifigures purchased. So you must have a minimum of 4 minifigures in your basket. For example if you purchase 4 you get the cheapest of the 4 free. If you purchase 8 you get the two cheapest of the 8 free.