On the Marriott side, there is a Guaranteed Room Type that would provide $100 a night in compensation. I suspect that would be on top of the room type differential since you would only pay for the room you received.

https://www.marriott.com/marriott-re...s/guarantee.mi

In a few thousand Marriott nights, I've only had this happen once but when it did, I received the guarantee in cash (although it was because they only had a double and I had booked a king).

Is there something comparable on the SPG side?