Should I take legal action against my employer for putting the incorrect info in the tax withheld section 4 W2

I got my W-2 and when i looked at the federal tax withheld section it was off about $800, however admittedly i did not keep my recent paystubs this being my first job i did not kno any better. i contacted my employer the second week in jan to ask for a duplicate paystub and the woman in payroll said they don't hav it so i figured i lucked out and i continued to file my tax and i got my fed refund but today i happened to stumble across a paystub from oct with the tax withheld already exceeded the amount they stated and from oct to dec i've earned about $3,000 what should i do to resolve this. as a side note i consistantly fight with my company with gettin paid and missing hrs, and checks altogether, so i don't believe this is a simple oversight on their part