Frustration occurs when we get less than what we expected.
When I rent a car, I never get frustrated when they tell me they are all out of economy class and I have to get an upgrade to a sports car. Frustration sets in when I order large fries and I only get a medium!
Frustration is more than unmet expectations. When I receive a free upgrade my expectations are surpassed and I feel the opposite of frustrated. I feel blessed, excited and surprised.