Yeah I thought that was the case, however, I have waited patiently thinking it would arrive at my apartment as they said it would come on the 26th. It's not that I was stingy, just thought I had gone about it the 'morally correct' way. As you say, it seems I'll end up having to pay.
I think Cambodia is one of the only asean block of nations still letting UK citizens in without any hassle. Getting back into Thailand is hassle though.
So if you are coming to the end of your first Non Immigrant ED Visa (like myself) and have already booked flights out (which I have just found out have been cancelled) then the best bet is to get a letter from the Embassy here in Chiang Mai?