Do you have a working surround sound system? My older (2008 build) has the CD/DVD as part of the surround sound amplifier.
RV dealer sales and service personnel have an overall reputation as being as honest and upright as used car salesmen. A common tactic of theirs is to "ROB" parts/furniture from one unit on their lot, which they never seem to reorder, in order to complete a sale to a current buyer who noticed the missing stuff in the pre-delivery inspection on HIS unit.
Most often what I hear what happens when you bring the missing equipment from YOUR rig to the dealer's attention, is they say that "It was there when we sold it to you" and it is your word versus theirs. Guess who usually wins???
Also, there has been an ongoing problem for MANY years with RV's getting broken into overnight on dealer's lots, and the electronics getting stolen (Usually the TV's). Most RV dealers remove at least the TV's to keep them from getting stolen while on their lots.