I think you need to ask Amex Travel (Orbitz) before reaching a conclusion. Everything you have in writing is correct. Just tell them that when you arrived at the hotel the property could not locate the booking, but discovered it had been entered for the wrong month, and you would like to know how this happened. The other details are immaterial.
Just the 800-297-2977 number for "modify trip" that's in the AmexTravel confirmation email? If they admit that was their mistake with the booking, should I ask for MR points for the inconvenience? The booking was one night but for $463 and did inconvenience a lunch reservation and theme park time. Would 2500 points be appropriate? Less? More?