My left low beam headlamp has experienced multiple problems in the last 90 days.

In early June the controller was replaced. By mid-July, the Xenon bulb color turned purple so I replaced the Xenon bulb.

Now, almost 90 days after the controller was replaced, the low beam lamp has failed again. Both were placed by a local BMW repair shop. Not sure if i trust them or not.

So, I took my car to the BMW dealer to get a fresh opinion on what's going on thinking they could easily diagnose the problem (what a mistake)..anyway:

1) the dealer has said there is power going into the headlamp assembly and they are recommending removal of the bumper and replacing the headlamp to see if that fixes the problem ($2500 parts + labor).

2) the dealer has also said to confirm if the controller is working or not, they have to remove the bumper; they also told me to replace the igniter they have to remove the bumper.

Question: Do they really need to remove the bumper to validate what's going on and to validate if the controller is or is not working.

Any other suggestions on where the problem could be: a) faulty controller b) bad xenon bulb c) bad igniter/ballast or d) the entire headlamp assembly needs to be replaced.