Is what the lawyer doing considered as malpractice?

Im filling in for my brother. He's in jail waiting for trial, but his lawyer completely stopped reaching out(answering his calls). His lawyer wont even reply back to me. My bother also said the lawyer assistant wont even answer his calls. I've been told by the assistant its because recently we've been behind payment (2 months), and the lawyer wont visit/reach out or continue to work on the case, until we're all caught up. Small payments are still being made dispite current money issues. We've always paid on time and in full. I dont know what to do... Advice needed. Please help.