My lawyer hasn't resolved an issue for a case settled 2 years ago, and won't return phone calls or emails. Can I sue for malpractice?

I was hit as a pedestrian in a crosswalk and hired a lawyer to handle the personal injury claim against the driver. Repeatedly, my lawyer said the other attorney wasn't going to budge and we couldn't get a higher settlement and juries in this area were not sympathetic so I should settle for a very low amount. Based on conversations, I don't believe he was actually negotiating at all but just telling me to settle so he could focus on other cases. I settled and all bills were to be paid and he got his fee. A year later, I received notice that I had outstanding bills referred to a collections agency and my wages could be garnished, etc. I called him and he didn't respond for a week (admin confirmed he was in office). Talked to a different attorney within firm and they were going to work together to clear it up. Never heard from them, but didn't get any notices so hoped for the best. Now receiving notices that balance is still outstanding, he never contacted the agency again.