Where can I buy a replacement stem for a Mya Saray Large Gyro Hooka?

I need to buy a replacement piece for a Mya Saray Large Gyro Hooka ( a href="http://www.hookah-shisha.com/p-1738-mya-saray-hookah-gyro-1-hose-hookah.html" rel="nofollow"http://www.hookah-shisha.com/p-1738-mya-…/a ) . Specifically I need to replace the stem (down piece, and shaft)