citizenship background check take 4 years

I need help!!

My wife had Citizenship interview at 2002, and passed everything, but been told we have to wait on backgound check!
Now 4 years late, we are still waiting on that!

We went USCIS Boston office 5 times, Boston FBI office, finger print 4 times, sent letter to state senators and USCIS Washington office, and the answer is still the same: Waiting for Background check.

Please advise us what we need to do? Should we apply again,or take some legal action?

Thanks