I have a reward booking at Wembley during the Rugby World Cup and am looking at changing it from a 2 night stay to a 1 night stay.

I booked when it was 10k per night (it's now 20k per night).

I know I should have made 2 bookings each for one night, but I didn't.

Is it possible to change to a 1 night booking and get my 10k back or is this likely to cause other problems?

The current cash rate is £299 and there are no reward rooms available.