2006 z4 headlight problems?

Hi, both of the xenon lights on my
2006 z4 went out at different times
over the past few months. I haven't
taken it into the shop because we
usually drive my boyfriend's car
everywhere so it wasn't that big of a
deal.
Both of the lights faded to pink, and
then from pink faded to an extremely
dull yellow color, literally couldn't see
in the dark. I don't know if that's
what usually happens with headlights
but my mechanic is saying that I
need a complete new control system
for $500 on top of the $200 per bulb
lights? Does this sound right? My
brights were working fine by the way,
even when the bulb was pink.

TL;DR: Both headlights went out at
separate times, mechanic says I
need new control system. Sound
right??