You may have encountered issues with the application of gift vouchers recently.
During the last few weeks we've been busy upgrading our checkout to allow for more payment options and currencies, but unfortunately we've needed to temporarily change how vouchers can be applied.
Previously vouchers could be applied against a purchase at either shopping cart or checkout pages, but at the moment they can only be applied at the former.
As long as a voucher is applied at the shopping cart page, it's value will still be deducted from the total due at checkout. Note that this may only be the case once you have fully entered your addresses and clicked 'Continue to Payment'.
This does mean that vouchers can currently only be used in full or up to the value of an order though, so it isn't possible to only apply a portion of the voucher against a purchase.
In the coming weeks we will return the ability to apply vouchers at checkout and restore the functionality to partially do so. Thank you for your patience in advance.
Applying a code at the shopping cart page:
Checkout summary after entering address and clicking 'Continue to Payment':
Please note the voucher code used in these screenshots is for demonstration purposes only and holds no value.