Thank you for your reply.
I tried emailing Hilton customer care.
Unfortunately they are unable to add my HHonors number to my booking.
Can you tell me if my concerns regarding being a second class customer are justified?
I entered the Honors number into my Expedia account yesterday (don't think that'll do anything) and will try the hotel itself next.
Does anyone know if the hotels have their own email address or do I have to call?