Then here are a few hints. If your fairing is made of what appears to be "fiberglass" (that is, it is relatively thick and does not appear to be "molded out of plastic" like newer fairings are), then it is made of something called Sheet Molding Compound ("SMC"). This is the same stuff that Corvette bodies are made of. It is a mixture of chopped glass fibers, polyester resin, a catalyst, other fillers, and some mold release compound. It starts out as a putty-like glob that is precisely weighed and put between halves of a mold. The mold is then closed and heat applied. The stuff flows out, fills the mold and then hardens.
OK that's what it is. Now the problem. The mold release they put in, is there to ensure it doesn't stick to the mold. It also makes adhesion to it very difficult.
So... if you or your guy need to patch cracks in the fairing, DO NOT use ordinary polyester "fiberglassing" resin!!! It will not stick!
Instead, it is imperative to use an epoxy resin. Not the sort of epoxy that comes in 2 tubes in the hardware store, but a proper epoxy such as West Systems "G-Flex 650" epoxy. It comes in a kit of 2, 4 ounce bottles for about $20. This is a "toughened" epoxy that withstands vibration.
The only problem with using epoxy is that the stuff is not nice and runny like polyester fiberglassing resin is. It is like honey. So if you need to repair a real bash, you will need to lay up layers of fiberglass cloth, and saturate them with the epoxy. The best way to do this is to suspend the part being fixed above a hotplate, and allow it to heat up to about 100 - 110 degrees F . Now, when you brush on the thick epoxy onto the part, it will instantly heat up and get nice and runny and "wet" the part beautifully. The other advantage of heating is that the epoxy will cure MUCH faster... in about half an hour, instead of a day.
As for more minor graunches, ordinary "bondo" filler (body filler that uses a catalyst) works well.
As for painting, once the bodywork is finished, you need to primer it with a catalysed primer like "PPG Prima K36", then sand with 400-grit wet-or-dry sandpaper, and then rub it thoroughly down with a Green Scotchbrite pad.
Final color coat should be painted with Glasurit paint. Glasurit is BMW's paint supplier and the have the original formula. Trying to get a paint match using another brand is a crap shoot.
Your bike should have a sticker with the "Finish Code" under the seat. My old K100's is #617. This needs to be looked up to get the actual Paint Code which is what they need to get the paint formula. In the case of my old K100RT, looking up the #617 Finish Code, results in a paint code #186, and the color name "Diamond Grey Metallic" (or some German equivalent ...in my case, "Diamont Grau Met.").
Here is the website where you can look up your own Finish (or "scheme") Code to get the paint code..... http://www.bmbikes.co.uk/paintcodes.htm
First, select the general color (in my case, I clicked on "greys"), then in the page that comes up, look down the Scheme Code column (I looked down until I saw #617), then next to it you will find the color name and paint code number (iin my case, paint code 186 and the name Diamond Grey Metallic.
Glasurit has a US site that gives locations US many US shops that use this paint.