This weekend I tried to change to 6000K bulbs on my headlights. But I failed

I removed my headlight and everything but I just couldn't remove the HID bulb from the housing. I tried turning it to the both sides and even pulling stright up and no luck. I didn't really want to force anything. I didn't want to break anything and end up having to fix a bigger problem at the end of something simple.
Can anyone help me out so I can try again next weekend?