Hello Yann_Y
That’s unfortunate. How did you travel from Chur to Zermatt then?
You should, as a courtesy, get a compensation for the Glacier Express seat reservations.
Do you have a confirmation from the IC train staff or SBB Travel Center personel stating that the IC was cancelled from Landquart, and consequently you missed the Glacier Express? Did you contact a staff in this unpleasant situation?
That you have not heard back from the Glacier Express service team sounds rather odd to me; from my personal experience, they are usually very responsive and caring. Try again at railservice@rhb.ch
Kind regards,
Roland