Trunk Wiring problems of the 2001 Chevrolet Venture

Purchased van July 2001. I have discontinued putting my son in installed child seat because he complains it hurts his legs; when he goes to get out he can't hardly walk;I think the position of the seat causes his legs to go to sleep. Since purchase of van I have had it in for service several times. (1) I complained of vibration in the front when I got up to a speed over 50 mph; the service techs could not find anything wrong. (2) I complained of (while traveling) hearing air ventilation (like a window was down) on the passenger side; nothing was found. (3) when purchased the vehicle we stated our concern that door did not retract immediately. I put my arm in to demonstrate; it pinched my arm and bruised it before it finally retracted (4) I have also had my van in complaining that the cd player did not operate properly. They said it was defective and replaced my entire radio/cd. (5) complained that while driving (noticing at night) my headlights would dim and come back on. After not finding anything they replaced the alternator. It is again happening. (6) recent concern is while on an upward hill at a red light water started coming in through the storage compartment between the visors. Now they are declaring that the windshield was not properly sealed when it was installed. I have had this vehicle now for almost two years. My thought is that it may have been leaking but now just to the point that I am noticing it. How much damage has it caused in my head liner, etc. That they will not be able to detect with the naked eye and is the air ventilation that I was hearing a result of the windshield not being sealed; and is the water leakage causing my shortage in the wiring of the lights and radio, etc. My concern is later down the road will I have more deteriorating problems because of water damage that could not be seen at this point.