Check the level of the automatic transmission fluid. The ATF is run by lines up to a cooling section inside the radiator.
In case they really messed up, look for ATF in your coolant, and coolant in your ATF.
Chances are your car lost a lot of ATF when they took out the radiator, and they forgot to put any back in to bring the level back up.
Well, that's my try at an Internet diagnosis.
Ken300D