To protest your taxes, you can use the following links:
Bexar County
https://www.bcad.org/index.php/Protest_Info
Kendall County
https://kendallad.org/appraisal-notices-for-immediate-release
Texas Comptroller Video Link:
https://comptroller.texas.gov/taxes/property-tax/video/homeowner-protest-ce/story.html
Good luck to you! 
Let me know how else I might help you!