The car started to burn out headlights after having the alternator and battery replaced (at dealership). It always starts on the passenger side, and I replace the bulb then about a month later, the drivers side goes out. I replace the drivers side and about a month later the light on the passenger side goes and back and forth. I was replacing them myself (with gloves), but after going through 8 bulbs I decided to say something to the dealer.

They replaced the bulb thinking that it might be the way I put it in and the bulb would be under warranty if it went out again ($56 for bulb and labor), and the master mechanic couldn't see any reason why it would go out. Then 1 month to the day the passenger side went out again. I took it back to the dealer and they couldn't find any reason why it would go out and the master mechanic looked at it, said there was corrosion in the wire and harness going to the bulb ($378 minus the cost of the bulb) so they replaced the harness, wires and the bulb again. I will report in about a month if the fix worked.