Flushing the cooling system has its drawbacks. I you needed one freeze plug, you can reasonably suspect the others are surely right close to failure.In this case, starting to fail one at a rime weakest first. Now, as far as the other issues are concerned. What is the question? Sounds like the tazmanian devil had too much time on hand. I don't know the qualifications or integrity of your mechanic, but I do know a reputable, as well asa professional mechanic is not likely to intentionally or even bother to, contribute to these describe issues. Ocassional blue smoke is an internal problem, The AC is an issue in itself, The caalyctic converter is an issue that is too messy, smrlly thing to deal with. Any evisence of how and of what it was gutted? What was repaired or listed as repaired on your invoice? And what state are you in? It appears you may be seeking legal advice and in this forum it would not be an appropriate place to seek it. You may want to refer this to an Attorney for assistance.. Good luck and I hope you reach some resolve on this matter.

Replace the thermostat first. when engine cool check engine oil if it look like milk shake. you got a blown head gasket.