How to get reserved VIP seating on the golden pass route from Montreux to zwiesemann
Better contact the MOB, as the cars with the VIP seats were taken out of service last year to refurbish them. I don't know the date when that work will be complete in 2019.
http://www.mob.ch/en/home/contact/index
Swiss reps told me they are not offering the VIP seats at all this year, or at least not before December, during the ongoing refurbishment.