Britney Spears' custody case has just suffered another blow - her lawyer is on the verge of quitting. The singer is currently embroiled in a bitter battle with her ex-husband Kevin Federline over the care of their two sons Sean Preston, two, and one-year-old Jayden James. According to TMZ.com, Spears' lawyer Laura Wasser will submit legal papers formally withdrawing as her attorney on Monday (17Sep07) . Reports suggest Spears was a "problem client" who failed to listen to Wasser's advice. The website reports Spears' new lawyer will be high-profile attorney Marci Levine. The singer and her ex were expected to appear at a Los Angeles court on Monday (17Sep07) to hear Federline's case for removing the children from Spears' care.