Stone Oak Clinic. Hours: Monday, Wednesday - Friday 7:30 am - 5:00 pm, Tuesday 7:30 am - 8:00 pm, Saturday Closed, Sunday Closed. 20821 U.S Hwy 281 N Suite 122 San Antonio TX 78258. Telephone: (210) 546-1600 Fax: (210) 546-1610..