How do I fire an estate attorney?

I hired him to minimize my stress as executor of mom's estate, and he's ended up being the cause of most of my stress. After my mother passed, I was overwhelmed with the responsibilities of being her executor. I wanted to make sure that everything was done legally and that obligations were met timely, so I hired the attorney who had last updated her will to handle the estate. His specialty is real estate and wills and estates. He was the only attorney I recommended to my clients when I was a full time realtor, because he was so good and his office was very timely and responsive. I met with him for an initial meeting, and he even offered me a slight discount on his hourly rate, because I had referred so many clients to him in the past.
My first clue that this experience would be different should have been when it then took 3 weeks and many phone calls to get a copy of a retainer letter so that I could actually officially hire him. It's been downhill from there. The paralegal who he has doing most of the actual work is incompetent - letters he says he sent never arrive, typos, numerical mistakes, etc. When I met with the attorney early on to express these concerns, he charged me through the nose for the meeting, but nothing changed. After almost a year of this, I've pretty much reached the end of my rope. On the 16th I received a cover letter from his office, dated 4/9 and postmarked 4/14, which was just slapped on top of a letter from the state auditor who is auditing the estate and inheritance tax return. Basically, it took them 2 weeks to send me a letter which then just asks me to do all the work. I have been working to compile the supporting information requested by the auditor; it's literally hundreds of pages. I tried calling his office to ask how best to handle/streamline the process, but, of course, my call was not returned. My stomach has been in a knot for over a week now over this, and I've also got insomnia. I also take care of my 93 year old aunt. At this point I am seriously contemplating firing him and just handling the audit myself. Any suggestions/experiences are highly appreciated. Thanks in advance.