Air conditioner dealer can't even fix.

2007 Toyota Camry hybrid just suddenly losses cold air until I turn the car off
and start it up again then I will have a cold air again.  Dealer replace the
condenser but it did not solve the problem.  Told me to come back when it
happened again and I did when it was not blowing cold air and stay at the
dealership for almost a day and they said they did not seem to find any
problem .  They told me to come back again and I did but the result was the
same and they did not refund me the money I paid for the condenser that did
not do anything.  Please help me if someone knows what it is.

Thank you Tommy B.