What’s the actual closing time ?

Hi there I trust you are well . This is more of an inquiry more than anything.. if I were to come to sorbet at 17:30 30minutes before closing time is someone not supposed to see to me irrespective of whether at that moment In time they’re busy and might only be done by 6pm which is when they close . I came in for a soak off and they refused to assist me because they didn’t want to run overtime ... it is to my understanding that as a chained store closing time means closing time and naturally the first available nail tech that’s done will assist me if I come in to a sorbet store that’s door sign still says OPEN ?