Their Facebook page says to email them if something isn't working:
"Earlybird should work on most items, only those that are in sale, on pre order, plus a few limited trainers such as the upcoming Jordan and Adidas Consortium releases are excluded.
If you are having problems on any item not listed above, email firstname.lastname@example.org"
What are you looking at?
ALSO, I know you have experience with End. Do they take the discount before VAT or vice versa?