Do you pay someone to protest your HCAD appraisal and taxes?

I have a subscription with one of the big tax protest firms (O’Connor). I pay 40% commission on any tax dollars saved. If they don’t reduce my bill, I don’t pay. It has saved me 1000s over 15 years.

I also just got an offer for $249 flat fee every year. The company name is evading me.

I also just found Ownwell on Google, for 25% per dollar saved.

I have nothing to gain from any of these, just sharing the suggestion. Share your experiences as well.