Thanks for the replies folks. To answer a couple of questions asked. I couldn't refuse because he already had asked for and been given my card before informing me the system was down. By "down" he meant that checkout staff could not access the system.
The card provider has been informed, reply expected today and a quick online check shows no transactions and no "pending" transactions either, not even the hotel payment. So far, so good!
The card provider has now confirmed that the hotel bill has been declined because some detail was incorrect. Maybe my constant whingeing must have affected the chap's concentration as he wrote.
s37