Juist as an afterthought, a specific example. Today, the GB pound is at all-time low against the USD. Anyone planning on visiting London next year should be seriously considering making their reservations right now.

Imagine making a reservation with Marriott this evening to go and have tea with the King next August, when it's clearly stated that "Prepay rates will be charged the full cost of the reservation within 24 hours of making the reservation." But it wasn't charged as promised, and the guest ends up hundreds/thousands out of pocket because exchange rates have normalised in the meantime. If this went to legal dispute, who is liable ?