Return shoes only if in "NEW" condition

Kingsmead Cape Gate won't let you return shoes if you've worn them. Their policy states that shoes must be in "New" condition when returning them. I did not even have the shoes for 24hours, but because they can see that it's been worn, they won't let me return or exchange them. Firstly, how are you to know if an item needs to be returned if you are not able to wear it first? How can an item remain "new" if you need to wear it in order to determine whether it fits? Secondly, if people are allowed to fit and wear shoes in the store, are the shoes then still "new"? Can it then be sold as "new" shoes? The shoes I wanted to return fit well, but unfortunately they started to hurt my toes as the front of the shoe is extremely hard and unflexible. I wouldn't have known this unless I wore them. I had them kn for 30minutes at most and it hurt so bad that I immediately went back to return them. But the store won't allow me to do so even though the shoes are still in excellent condition, except the sole has 2 small scuff marks on. Which by the way, can also occur when you try them on in store! My house only has tiles, just like the store, so I don't really understand how they can refuse to let me return them.