How can I force my attorney to give me an itemized bill for services rendered?

I signed a retainer for estate legal representation. The attorney asked me for additional funds which I provided. I am unable to get a bill for services rendered (have been trying since Dec) There is no doubt the estate has been overcharged as per the retainer agreement. I am the Executrix and am trying to close out the estate. The majority heir wants to see a copy of the legal bill. The attorney was very clear that he did NOT keep track of appts, phone calls etc. What can I do to force him to give me a full accounting and/or refund?? Any suggestions you can provide would be greatly appreciated.