Proof the Bombshell should be nerfed?? Check out this game I just had...

[The RawkHawk]

Rough game there - although from this game I wouldn't go so far to say that shell should be nerfed.
This is a really tough level to play against the scallys; the small corridor combined with plenty of cover provides excellent vantages for shells.
In this particular game - I would say your trouble was a combination of your limited map awareness, and being a tad too eager to rush a defended shell.
Position a strategic runner or two so that you can make more intelligent decisions based on the location of their units.
When attacking a shell, make sure you set up a smart attack instead of attempting to charge directly at it. Sometimes a rush can pay off if your opponent has overextended themselves without the wits - but often times you'll just end up feeding the shell. My favorite way to kill shells is a sniper, runner combo - but then again I play the Adorables.

Gotta love me some Moo.

Anyway - let me know what you think about these suggestions, I'm no expert by any means. Good luck with those future turtles.