Dear ElenaLH
Thank you for your question.
You need to purchase a CHF 16.00 upgrade for the seat reservation and the Gotthard Panorama Express experience. To purhcase this, select “Reservation only”.
Plus, if you have a Swiss Travel Pass in the 2nd class, you need a class upgrade from 2nd to 1st, because on this panoramic train there are only 1 class carriages. You can buy the class upgrade on our website Class upgrade for a route or for a day | SBB
You can also buy both upgrades at any SBB ticket counter.
I wish you a nice day.
Kind regards
EleonoraS