Well, the CT thing would be a problem. I don't think we'd cover the flight costs for a 1 hour problem.
About payment, we would pay the person doing the job, and claim back from the client (so no chance of the client screwing the person). And if they call for every problem, we charge for the time spent on the phone. And if they don't pay, I can't afford lawyers, so I'm happy if I've done enough damage to them to cover 10x the expense they've screwed me out of.
We've never not been paid

We have been screwed out of a huge job once by a someone we thought we could trust. I'm waiting for the person to get back into the country so I can "discuss" this with them.