I have sent a certified letter requesting my money back with no response.
Criminal Defense Attorney
First, you need to make sure you appear at your court dates so that you are not accused of failure to appear. You should probably hire another local attorney to handle your matter to conclusion. As for the attorney, once you have given the attorney time to receive and review your demand for funds returned, you should call the local Dallas bar for assistance or call the State Bar of Texas for help. They have a group dedicated to helping citizens. Good luck and make sure this Attorney's failure doesn't negatively impact your criminal charges.
DUI / DWI Attorney
You are entitled to an answer. Call his office and demand one. Write another letter, send certified, and inform your lawyer about the missed court dates, documenting them with a copy of the docket sheet or scheduling order from the court. Give him a deadline of 10 days to provide you with an answer and notify him that your next step since you have not heard from him is to file a grievance. If you don't receive an answer to your satisfaction, file a grievance with the State Bar, including all of your documentation. Then go hire another lawyer but research them first. Search Avvo or www.NCDD.com and get references of former clients and call those former clients.