I added the extract from the rule sheet later, so I suppose you haven't read that yet. It is also the responsibility of the purchaser to know what they are buying. Sellers cannot be expected to take every possible misinterpretation of the rules into account.

Besides: if you had reissued a ticket from before the discount when the 10% discount was in effect you would have gotten that discount too. It works both ways.

I understand your frustration but that is just the way it works. xONEx tickets are a bloody good deal so no sense complaining.