Not sure if this helps you or not, but I've been hearing commercials for Statewide Remodeling that specifically promote a special they're running on walk-in tub remodels. Never used them before so I can't speak to their prices or quality, but the owner does the ads and his voice sounds like he smokes a lot, so that has to give him some contractor credibility.
I'm in Dallas but I believe they have a Houston office as well.