Undertray near rear brake lines

Hi all,

I expected to find a quick solution via google and forum searches but sadly haven't. There are to rear under trays on my fabia that cover the middle outer side of the vehicle including the rear brake lines. Both are hanging off but rather than using under tray screws, it appears they need some sort of wing nut to hold in place.

Any idea what size/type I require for the job. I've had a look on ebay searching around 'fabia under tray wing nuts' but have found nothing yet....

Many thanks to anyone who can help