Take her to court. The more she owes the more likely she is to stop coming around. Or you may get a judge that is ruthless to her and will throw her in jail until all back child support is paid in full. My wifes ex still owes her over 30k for our daughter who is turning 30 this year. He has not seen her or the grandkids in a few years and may never see them again because my daughter is tired of his crap.