how about medical test in original country? You can claim refund from Philippine consulate for the insurance their govt charged, it is not transferable, over ˋ1000.
Suppress your number when you call, press 133 first (not sure about code to block own number) before you call agent. Tell agent if you do not ask for 1 month notice from the maid and will give her a plane ticket back plus $100 travelling allowance as per contract, if she leave you alone.
Fax the resignation letter to Immigration ASAP, I think you need to fill a form, she has to fill in a form too, but I guess she will not do so now. The standard immigration form has to be signed by her, listing that she resigned. both employer and employee have forms to sign .within 7 days of termination of contract need to reach Immigration Dept.
If you really go to court, ask Immigration to ask for it. The agent may have it on file, or the Phil agent has it. Of course, you can't rely on it,but you will not lose anything to ask for it, why not ask?