Lady Sandy used her high heels to show this guy that she did not like his bigoted tendencies. He did not like to be told anything and he took offense at what she told him. But he was soon begging her for mercy as she used her high heels to trample and torture him so that he learned his lesson. He dropped his bigoted tendencies after what she did to him.
Lady Sandy does not like proud people and this guy was one. She did not want to deal with him but he could not stop trying to get her attention. The mistress used her high heels to trample him and make him realize that she did not like his pride. He was forced to swallow humble pie and he changed as he did not want to experience any more humiliation.