Bad service

My mother bought a pair of shoes for my daughter however the cut is small she gave me the slip in order to go exchange the shoes. I went to Soshanguve plaza store and I was told that I can't exchange the shoes because I don't have the writing consent from the account holder who bought the shoes therefore they wont exchange them. I asked to speak to someone then the lady called their head office where I spoke to Mbali I explained the issue to her she then told me it is their policy and hung up the call on me.