My buddy's seatstay was repaired by Ruckus Composites in Portland. Unnoticeable w/ clear coat, ~$350 + shipping IIR.
I've never heard of a CF repair that failed or had later problems.
I did it myself w/ $40 kit. Good result but didn't try to match the paint exactly.
To get it done professionally you have to completely strip the frame, then pack, ship, & later put the bike back together.
