See the article on RUB RAIL replacement in the FAQ:http://continuouswave.com/whaler/reference/FAQ/#Q13
For the black vinyl to become detached from the plastic receiver track is quite common. Heating the black vinyl rub rail insert with hair dryer will make it more pliable and easier to push back into the plastic receier track.
If the plastic receiver track is detached from the hull, it must be mechanically re-fastened to the hull. See the FAQ for methods to accomplish this.
If the vinyl inset is broken from the original one-piece, the best repair will be to replace the vinyl with a new one-piece.
If the plastic receiver track is broken, you can, perhaps, replace only the broken portion, but only if you are willing to accept a clearly visible joint line.
The OEM supplier--as far as I know--was never SPECIALTY MARINE. The actual OEM supplier is listed in the article linked in the FAQ, and you can buy the components of the rub rail from authorized Boston Whaler dealers.