Free honeymoon!
All been confirmed. We get double the difference back.
Alas, the biggest catch is that I don't get the money back until 30 days after the trip (but at least I won't be able to spend it in the meantime

)
Boy, are we going to get fat at the restaurants now!
EDIT - advice: if you were to do the same thing, I recommend calling their customer service number to get them to confirm the guarantee within 24 hours rather than waiting for 3 working days for the reply promised in their T&Cs.
I never got any confirmation of the details I sent electronically, except for a computer generated confirmation. It seemed that this info was lost. Instead I was asked to send them an email showing this computer generated reply as proof that I had acted within the required 24 hours.
Nevertheless, this has been a positive experience for me, the people I spoke to there were very pleasant, and they didn't give me the impression they were out to trip me up in any way.
I'll be happy to use this company again as they do seem to have a lot of genuinely good deals (most of which include breakfast or other meals - but this is another reason why it is hard to make like for like comparisons with other sites such as Expedia) I'll post the eventual result (i.e. whether I'm given any hassle re. the refund) as it's always nice to know of trustworthy travel agents on the web.
Oh, and thanks
PappaG!