A deal is a deal and they should honor it - in fact if it was struck up via email it would constitute a contract... But then a lot of people tend to just consider email a throw away... not worth the 'paper it is printed on'. So it is not for them to be asked to reconsider - they agreed to it in the first place, they have to honor it... but I doubt they will.
On the up side... does that mean you might have some earlier editions of your coins to sell/trade?
Keewee