I am being deliberately vague here, for privacy reasons.
Earlier in the year, we booked a festive day-out event with relatives. We all agreed on the date, so DH and I booked and paid. We offered to pay, so that's fine. However over the weekend, the relatives have been invited to an extra event, which overlaps with the original event. We would need to leave the day-out just after lunch, missing half of the things we wanted to see/do, if we were going to get the relatives back in time for event 2.
I've told them we can't make it work logistically, so the ball is in their court. They are still deliberating and I'm really hurt and cross. I think this is really rude - if you have plans, then you stick to them, even if you get a better offer?