I have bought a Day Saver Pass as i plan on travelling Zurich to St Moritz for a day trip. I would like to catch the Glacier Express from Chur to St Mortizt. Do i have to purchase a seperate ticket for this leg of the journey on the Glacer Express website (87CHF) in addition to the day saver pass, or do i only need to reserve a seat for 13CHF? if it is only reserving the seat - how do i do this on the website ? (The drop down menu for discount does not include option"Day Saver Pass')