You may have a case by filing under Canadian APPR. If Westjet is blaming it on crew availability, that's typically a covered reason for both compensation and expenses. I'm not clear if you tried to claim under APPR with Westjet already, though they did note that you might be eligible for compensation under "other regulatory bodies" in your DOT complaint. If Westjet has already denied your claim for expenses & compensation under APPR, then you can open a case here: File an air travel complaint