Not sure why you would jump ship over this. Do you expect:
1. To be able to skip the first leg of a multi-leg flight trip and get refunded for it?
2. Make a car reservation for 7 days, then want to change to 6 and get a partial refund?
Rates change and most require you to rebook at the current rates. The only option (IMO) is to suck it up and eat the loss since your plans changed, or cancel and see if the Exec Room opens back up at the same rate. However, it might not, and you'll be stuck with the lower room.