San Antonio's Mexican Restaurant

As of Sunday, Oct 8, San Antonio's refused to honor Bulldog Card which plainly states 10% purchaseThis is all card saysHowever, San Antonio's made a homemade sign that read Bulldog Card only good on Monday and ThursdayI feel they should have to honor card all days of the week since that's what card states - it's not limited to certain daysIs this not advertising? Would like to hear from restaurant manager why they can do this and not honor card