As a mere man, I am somewhat loath to enter the bear-garden issue that is women's clothing, but ......
If she was a receptionist, it is likely that visitors would be looking at her face, not her feet, so I fail to see what difference her choice of shoes make to her doing her job.
I am also not sure why any dress code would insist on women wearing such an intrinsically uncomfortable style of shoes. For her to be dressed smartly is one thing...this seems something else altogether.
I say she should stand by her guns on this issue !