1996 Toyota Camry Radiator Replacement Question - Please HE

Engine Cooling problem
1996 Toyota Camry Two Wheel Drive Automatic 99,999 miles

The radiator in my son's Toyota blew the other day and he had a new one installed then next day. Later that afternoon, the car overheated. The "new" radiator was EMPTY. The radiator now leaks and is empty after driving a few miles. The garage that did the work told my son that the car could not handle the pressure from the new radiator, accused him of driving with a bad radiator prior (not true, first indication there was a problem with old radiator was when the car over-heated. It had held fluid until this happened.) The mechanic told my son that the plug blew as a result of the "new" pressure from the "new" radiator. They then stated that this plug is behind the fuel pump and that it would cost an additional $225 to fix this. My son called and talked to the owner and was told there was nothing they could do. I feel that because of his (our) lack of knowledge, he is being ripped-off. I would like to know if the plug blowing is a valid excuse for a new radiator not holding water. I would like to have some knowledge before I call them to complain and give them a chance to stand behind their work before I file a complaint with our county's consumer affairs office. My son is 18, works full-time and goes to school full-time. I hate to see him taken advantage of this way. My apologies for this post being so long. Any advice is GREATLY appreciated! Thanks in advance,
Lisa Bendel
lisabendel@tampabay. Rr. Com