I've been told by two repair shops (where I had my car in for other repairs) that the ignitor is dead for the right Xeon HID on my 2001 A4. I really would like to fix this myself, but don't know where to start.

1. How do identify exactly what to buy in order to replace what they have called the "ignitor". Ebay the whole essembly? Or just find the part seperate? How can I make sure i'm buying the right part?
2. How do I swap them out? Is this a procedure that has to be done with the car battery disconeced? Is it as easy as pull out, unplug, etc? Can anyone quickluy walk me though how to do this?

Thanks everyone!