Thanks enigmabear I contacted the seller and he mentioned that he
received a few messages with the same issue today, so it's probably as
you mentioned a glitch.
There are 19 items in Terms & Conditions listed
here:https://pages2.ebay.com.au/Buyer_coupons/promise From reading tthat
page I don't see any reason why I can't apply successfully for that
coupon code.
