The lawsuit has already been filed by this attorney. Does this make a difference?
We have a deposition scheduled for this Wednesday.
I'm not understanding exactly. The "lawsuit" (against you??) has "already been filed" by the attorney and you have a "deposition"? Do you mean he's made a motion before the court and there's a hearing for Wednesday? You definitely need another lawyer, because he'll probably be allowed to withdraw, but you may need to have conditions imposed to protect you. Let's hope he's sued the bus company, figures you don't have much of a case (this is a contingency case, right, where you haven't paid anything to the lawyer but he will get a cut of any settlement or verdict), and you can take the file to another lawyer with more enthusiasm for your case. And if he's truly just sat on your case, there are possibly malpractice damages against the lawyer or you can complain to the state bar authorities and the can discipline him because "diligence" is an ethnical rule for attorneys most everywhere. Discipline means written warnings, suspension or license or even disbarment.
See another lawyer quickly. You can find one on Avvo near you who works in the "ethics"/"professional responsibility with the "find a lawyer" tab.
And don't forget the tip jar (helpful/best answer) here. :-)