Water leaks are very hard to duplicate. The technician gets in the car, the lot person sprays the car with water. Tech uses a flashlight to try and spot leak. Removing panels and such. It is hard to get the water hose to be exactly like rain water, it just does not go into the same places at times. keep the faith, they will find it. If you want try another dealer. They are only as good as the people that work there. Just remember, they are people just like you...