Fwiw, my lawyer and his assistant are very responsive. Usually same-day response, often within a few hours. Not cheap, but I feel I am getting very good representation (I actually got a second opinion from a highly-regarded lawyer in the field, who reviewed the legal correspondence in question and concluded that my lawyer was doing a great job).

I do think the quality of service varies a lot. Would it be prohibitively expensive or difficult to do some research re disability lawyers, and possibly switch to a better / more responsive one?