Well that is definitely not good for the cable. It may not be catastrophic though.

Does the skipping (since the bike isn't trying to jump into other cogs, what you described is called "skipping") happen more on certain cogs? If so, which ones? Does it make a difference if you have shifted down into the problem cog or up?

I don't know why the LBS messed with your front derailleur. That seems to have just gotten your shifting even more screwed up.

Try loosening the FD cable (turn the barrel adjuster on the frame clockwise) and see if that lets you shift into the small ring. You may need to really loosen it. Then, once you're in the small ring, see if the chain is rubbing the cage. If so, then it could also be they set your lower limit wrong. Loosen that limit screw (the one closest to the frame) until there's no more rubbing. If you get rubbing now in the large chainring, then you probably loosened the cable too much. Shift to middle ring, tighten cable, then check up and down shifts again.

As for the back, what other information can you give? In addition to my first questions, is it slow (a hesitation) to shift in either direction (inward or outward)?