Mistress Christina had warned her slave not to piss her off but he did not listen. He did the very thing he had been warned about. The mistress had no choice but to teach him a lesson. She did this using her high heels. She crushed his head as well as his face to make sure he learned his lesson the painful way. He could not blame anyone except himself as he had been warned.
Even with super high heels on Gail is able to walk on her friend's face. Dents are seen on his face and she is not feeling sorry for the humiliation and punishment he is going through. He asked for it anyway, right? Naughty boys deserve for some brutal headstanding and foot trampling.