As a mere SLF (which group actually do the PAYING!), I 'd make damn sure that I never used that airline again - and would advise everyone I knew to avoid them like the plague. At the end of the day, delays like this are costly to the SLF - charge their time at £50 per hour, and the airline owes them! No matter what the delay is caused by.
Think of it this way. You need your car to get to work. The garage doesn't fix it by the time they say they will, don't provide a replacement, and it's too late for you to do anything about it. Wouldn't you be p****d off with them? No matter which innocent got in the way.
There's a fine line between acceptable and unacceptable behaviour at times, and as a very frequent flyer, I find that the airline industry has more than an occasional tendency to get very arrogant with the people who pay. No SLF = no jobs (except for the freight dogs)