When W-2 is incorrect, you think, on purpose - WaryOne

I just received my W-2 from an employer who consistently paid late for the last 1-2 years. The employer has yet to finish paying me for work from the last quarter of the year and is about $600 to $700 short of what he owes me. The W-2 reflects the whole amount that I had earned instead of just what had been paid by the end of the year. Has this happened to anyone before? If so, what did you do?

My feeling is -  not only that I cannot file an incorrect W-2 legally, but also that if I file with this amount that it would somehow document that I agree that I received the money and then he might be off the hook to pay the rest? Does this somehow help him in his "financial world" to say he paid everyone all of what he owed them when he did not?

I am not sure how many employees are out there that still have yet to get all of their money and may have received their W-2 without realizing it might reflect the wrong amount he actually paid them. Any advice? Just as a side note,  I no longer work for this employer and they are no longer contracted to do the work we were doing last year.