If you go to Dept of Labor, you run the risk of having your employer cancel your 401K plan. "Administrative costs too high, etc, etc." Then what do you do? What do you gain?

I'd say if you think these folks are honest, you would be best off to grin and bear it. Keep on their butts to get your account credited promptly and correctly. As time goes on, they will probably start doing a better job. If not encourage your employer to find another plan with more capable people (and better choices).

A bit of diplomacy here could be helpful. You can always threaten to call in the law as a last resort, but don't hurry. You can also damage your future with the company if you are not careful.