Fill out the comment card, with a note that you'd like a response within 48 hours. If that doesn't get a response, and if you can't reach a manager at their ski school, there are other ways to make their lives miserable ;)
Here's their Facebook page:
https://www.facebook.com/FernieAlpineResort?sk=wall
Here's their Twitter account:
https://twitter.com/skifernie
Here's their YouTube channel:
https://www.youtube.com/user/FernieAlpineResort
I'd start off nice on their Facebook wall, mention that you'd like to speak to someone directly about your experience with your lesson recently but that you're not having any luck reaching someone and that your comment card has gone unanswered. Don't put your phone number on their Facebook wall - there's enough information there for them to contact you.
If that's not answered pretty promptly (within two days, max) start ramping it up. Keep a list of the dates you tried to contact them, and what dates you posted on their Facebook wall. Also make note if they're deleting your posts on their wall. You can also write on your own wall with a link to their wall and it will show up on their wall (unless they block you, in which case I'll help you escalate it further because that's just really bad customer service).
With twitter, post an @SkiFernie message, which will show up in their feeds. Same route, if you choose to do Facebook first (which I think is more effective) then you can pick up with the tweeting at whatever point you need to.
On YouTube, you can post directly to their video channel. It will show up anytime someone visits their channel. As long as you're polite I don't think there's a way for them to block you.
I think at the *very* least they should offer you a free lesson with a different instructor. They placed you in that class, and the instructor chose to ignore your needs during that class.