My absolute worst:
Flew from HOU to STL on SWA. Arrived but a storm was on the field with lightning around so they closed the ramp. After a few min I called crew sched to let them know I would be a couple min late. Shortly after we were able to park so I called them 23 times before they picked up. By that time I was standing on the aircraft, just starting to board, looking at another FO. A reservist that was already at the airport. According to our contract I should have been given the flight back. Crew scheduling said "We know what's in your contract but we can't afford a late flight so tough". I said "I've been calling for the past half hour and no one ever picked up, I was here in plenty of time." Their response was that they can't help it they coudln't get to the phone. So i sat in base for 8.5hrs to wait for my flight to do a round trip to EWR. Lost 6hrs of pay on that one.