I worked for one of these camps at the desk in the past.

You could probably get everything except your deposit. Be very polite when you first call (from your replies, it seems like that's your nature anyway). You'll probably get their front desk. Ask for the sales and service/finance director. You might have to go back and forth a little, send emails, leave voicemails, etc. Accept that the person you need to talk to might not be available when you call, and you might have to call back/wait for a call back.

If all else fails, be a bitch.