repo-ed

I got divorced in 3-2002 my ex- was awarded a a car and agreed to make the payments in the divorce decree. She let it go back to the bank and since they couldnt find her they came after me for the difference of what they gave it away for and what was owed. I refused and tried to make a deal with them on paying half if they remove it from my credit and go after her for the other half they refused. Its been on my credit now since then 2002, recently I was trying to qualify for a house and there it was on my credit only now its showing as being posted as recent as 2006, but still no contact with them on this matter just a charge off I believe, now I am getting calls on my cell phone from them, how they got my number I have no idea isnt there some kind of statute on this and what can I do I am recently laid off and can not afford to fight these guys with my own lawyer. Any Help?