Heather Mills is facing legal action from her former lawyers over $4 million (GBP2 million) in outstanding bills relating to her bitter divorce battle with Sir Paul McCartney. The ex-glamour model was dumped by legal firm Mishcon de Reya last month (Nov07), after she embarked on a string of print and television interviews to rant about her divorce from the former Beatle. But Mills, 39, has yet to pay for the privilege of the attorneys' services - an amount which was incurred over an 18-month period following her split from MCCartney in May 2006. Mishcon de Reya had previously agreed to collect payment upon the settlement of her divorce, but that deal was void once the partnership ended in November (07) - reportedly because Mills defied a gag on talking about the couple's daughter Beatrice, four. And now the legal firm is set to sue Mills - who is alleged to be living off an overdraft from prestigious London bank Coutts, according to reports in British newspaper the Evening Standard. A source says, "Heather has been told she has to make steps to clear the debt. She has been told that a writ is as good as on its way. "Mishcon is acting as any business that is concerned about recovering a bad debt would. The firm worked tirelessly in difficult circumstances for Heather and it is now concerned it may not get its money. "Mishcon is concerned that Heather could get a nominal settlement of a few million pounds. But because she has other debts to clear, there is a worry that Mishcon will be at the back of the queue. Issuing a writ will at least make sure that it has a much greater chance of recouping the debt swiftly after the settlement. "Mishcon has drawn a line under its relationship with Heather. The thinking is that by going so public with a raft of accusations in that round of television interviews, Heather ruined her chances of getting a reasonable settlement." Mills' representative was unavailable for comment as WENN went to press.