I had a similar problem, my remedy was; The spoiler has to have been off at some point due to the presence of the steel rivits ( PO obviously mislaid the originals) if you remove the rivets and carefully remove the painted part of the spoiler, you will see two holes on the ends of the remaining spoiler. At the bottom of the holes you will see the head of the pins which hold on the spoiler body. These were fitted at the factory using thread lock. A 6mm allen key is needed to remove/tighten these (dont forget the thread lock.
