CRACKED HEADS

[diabolic hippo]

I just did my heads 2 months ago, installed ferrera titanium springs and retainers, upgraded valves, it was ok for one month then it starts to run hot 3/4 temp, so i took my car to a radiator shop who specializes in radiators and cooling systems, the could not diagnose the problem, so as seen on my other post on temp gauges, i replaced everything, wtr pump, water temp switch, upper/lower hoses, thermostat, cap, coolant, still same results, no oil in the coolant or white smoke coming from the exhaust, could not figure it out so i took it to the dealer, they diagnosed the radiator was plugged, i just had it check by a shop that only works on radiators and they said there's a little scaling inside though it does not need to be replaced, so i let the dealer replace the radiator, took the car home, it overheated the next day, took the car back, had to drive with the heater on, then they diagnosed the sending unit and a sensor, took car home, overheated a week later, i had the car towed to the dealer this time, now they can't figure it out either and there saying its either the head gasket or the cylinder head might have a hair line crack, so i can come pick up my car and take it else where or take it back to the shop that did the heads for a warranty and they will refund my money for the radiator job.
do you think the dealer should be liable for the heads because they misdiagnosed the problem twice?