I just need to exchange the shoes

I bought shoes on the 26/10/2018 at Zara Tygervalley. The first time I wore these shoes I didn't notice any issues as I didn't walk for long. The second time when I walked the ankle band slips off my feet and I have to constantly put the ankle bands back on, this happens every minute of walking. Wore them the 3rd time and the same thing happned so I told myself I cannot go on like this let me take these back to the store for an exchange. I bought these shoes for R559.00. When I got to the store I was assisted by Deka who is a store manager. Deka told me that there's nothing wrong with the shoes and that it's a "personal discomfort" and that there's nothing she can do. How am I supposed to wear shoes that come off my feet?? she told me to go to a shoe maker to get them fixed. I have never experienced such poor customer service in my entire life. I do not want my money back I want them to give me a different kind of shoes with the same price. I found this Deka telling another customer the same thing of "personal discomfort". I am soo disappointed with the service I got.