Although I havent this problem, I can see what u mean for such a major componant it's very flimsy not even a rubber shroud over the plug.
All I can suggest is have a look in a Maplin shop or RS or Farnell componants on line..Have you try'd a repair with this 'apoxi putty' thats on the market, u know the one that has two parts which u cut and mix together, U can then form form a new shell around the existing cracked one. Just a thought.
Regards