1994 Ford Explorer car running hot

I ttok my car in to have the air recharged long story short while they were doing the work they overheated by car so bad that the car would not start little lone run and antifreeze was boiling out all over after another 4 hours at the shop and me watching as they left the car unattended again for over 20 minutes and the car heating up again well past hte last white line they said they could not figure out what hd happened to make it do that? Well it had never heated up like that for the 4 years that I have owned it. Today they have repalce all the collaint, thermast, and couple other things but low and behold it still heats up? They will check the raideator tomorrow and see if that's the problem. My biggest question is will my car always heat up now and what are the chances that they may have done damage to the engine by allowing to heat up for that long of a time?
thank you for your time