When was the AMS service cancelled?
I'm not experienced as the others, but I would have thought that a scheduled departure from LHR of 6PM the day before could leave enough time to find alternatives, from flying to CDG/BRU/DUS even on other airlines, or use the eurostar, and then going with a rental car or a taxi to AMS in time for the morning departure. I think would have been cheaper anyway than a lost trip and a new ticket.