No assistant lake of customer service

I bought wrong size school shoes for my son on the 4th of April knowing that he will be wearing the following day when schools open. I took size 13 instead of size 1 because he was not they at the time I bought the shoes. He wore the shoes at school because he had nothing to wear , when I went for exchange at The Hub at Galleria I was not treated fairly as a customer. The cashier by the name of Wadine said they cannot exchange because it is used already. I asked for teamleader then came Lorraine who never entertained me told me from far that we will not change no matter what. I asked for manager I told her I will not speak to her because she is rude she doent see me as a customer then came Cliffy a manager who was not bothered in helping me either who didnt have any solution to my problem.