Dont buy cheap off ebay etc., they often cause problems.
Try autovaux, they are usually pretty good. If you are unsure, phone them, tell them what you need and the reg. number.
http://www.autovaux.co.uk/LoadPortal.aspx?cnum=11&pnum=AS90530463&tabid=5&vnum=129
Check the price at your Vauxhall dealer too. It will be expensive, but it will be the proper part.
fred, December 2009