Slow and Rogue solicitors make the whole profession stink. But they don't seem to have the balls to sort it out.
He's obviously milking the estate for all he can get (plus some for his cronies in Trade).
As he's making your life intolerable, how about trying the same on him. Harass him mercilessly, report him to the Law Society, report him to Trading Standards, haunt his office, telephone and e-mail him persistently (I've used this tactic successfully on conveyancing).
Incidentally since you are beneficiaries why isn't the house now yours - did the Will specify it being sold before distribution of the estate ?
You could take him to court for mis-handling the estate, but unfortunately these Lawyer folk will just close ranks and you will lose the case and have horrendous expenses. Such is our glorious Legal Profession, forever on the Make.