I agree, you don't always get the best diagnostic tech when you go to the dealership.
You may get some young trainee who is not familiar with the car and just start throwing parts on it until it's fixed.

The shop foreman are not always the best at diagnosing either.
In the future, If you did not already do this when you took your car in, make sure you request their( best diagnostic tech) in the shop and make sure you talk to the service manager (before) letting them touch your car.
This can go a long way in making sure they stand behind the repairs especially if they start throwing parts at the car left and right to no avail.