crap i only have 3 ambien left

my effing doctor only gave me 30 pills of ambien. and i see him every 90 days or so?
wtf. no refills on my ambien.

yet i get 120 xanax and 2 or 3 refills on that?
i dont get it...
i mean im supposed to take 4 xanax a day but that still doesnt make sense.