Almost all hotel sites and chains offer some sort of price guarantee, but in practice it's almost always impossible to get. I've tried several times over the years and I've had 0 success so far.
A couple of examples I have just from last night:
Booking.com -
Claim rejected because the name of the room is "different". It's actually the same along with everything else such as free cancellation date/time and meals, but they decided to put in "free transfer to Burj Khalifa" in the room name to avoid being the same as every other site!
IHG -
"The reservation is not booked under the lowest priced rate for the room type you booked." - but anything cheaper than what I booked would be non-refundable rates!
Does anyone know why that's the case? I was under the impression that hotel profit margins should be relatively big, or at least if you try to claim with the chains themselves (IHG/Accor, etc) there would be more success as you're cutting out the middle man…
Try Hotels.com, they have some kind of guarantee if you read all member info