It sounds like you are going through the TX A G office. Right?
Hire a private attorney. They will hire a private process server and get him served. It costs money but it's faster & it works. You need someone motivated.
Look on this website & find someone - like the attorney that has already answered this question.
Fran Brochstein has over 20 years legal experience & enjoys educating the public about Texas laws. She is a full-time family law mediator in the Houston area. If you found this answer "helpful" or "best answer", please select the button to show your appreciation. Please understand that this is not a personal consultation and in no way creates an attorney-client relationship. You are strongly encouraged to consult with an attorney in your county in person about your specific legal problem. You can contact her at 713-805-9591 - 7 days a week - her personal cell phone.