All M5 owners Please help!

I have bought the M5 infill plate for the rear number plate (3 months ago actually) but haven’t fitted it yet because I can’t locate the correct boot (trunk) lock surround. I got the part suggested on the forum #51 24 2 230 4311 it doesn’t fit way to small! The dealers are useless as usual when it comes to cars this old and nobody else knows. I’ve trawled the ETK and cant find it so I was hoping somebody here might have some new info to help or has anyone got an M5 with this part, and can let us know the correct part number. I’m sure it would be of help to loads of us in the same predicament.
Thanks in advance

Pics coming soon as I get 5 minutes break from uni, nothing special but I love it!