The Texas DTPA (Deceptive Trade Practices Act) allows the defendant 60 days to make a written response to the DTPA demand letter. If you get a DTPA demand letter, you should start counting the 60 days from the date you received the letter.
You can file a written response on your own or you can hire an attorney to assist you. Most attorneys in Texas have some familiarity with the DTPA but understanding the nuances and finer points of the DTPA requires someone who practices regularly in consumer law or is Board Certified in Consumer and Commercial Law by the Texas Board of Legal Specialization.
For your purposes, if you are going to tell them to jump in a lake or kiss your backside, you can do that on your own or hire any attorney to write that letter. If, however, you are concerned that you may have some liability and/or exposure under the DTPA, then you probably could use someone who understands the details and nuances of the law.
As someone who practices both DTPA defense and representation of consumers, it is easy to tell if the attorney writing the letter actually understands what they are doing. You may want to know what your probable liability and exposure is and will be under the DTPA. In Texas, if you respond in writing and make an offer in response to the DTPA within the 60 day period, you can freeze the attorneys' fees and the damages the plaintiff can recover IF THE PLAINTIFF GETS ESSENTIALLY LESS THAN OR EQUAL TO WHAT YOU OFFERED in your letter. Now that's worth knowing about!