Where can I get a replacement main beam bulb holder?

The previous bulb holder for the main beam perished due to melting and corrosion. Only found this out when I repeatedly replaced the bulb and it still did not work. Now I need a new bulb holder for a 2006 zafira. Drivers side if that makes a difference. Other car headlights have a clip which secures the bulb in place. This type needs the bulb holder to be twisted to keep in held in