Unfairly treated

I bought two pairs of shoes at rage last month on the 8 April 2019 at Rage in Polokwane. I tried to wear one pair and the heel felt like it will break. Went to the shop in Polokwane town yesterday and they refused to exchange shoes to other types for me. They are telling about your 30 days policy and I was away due to work. How do you expect me to wear shoes that are not comfortable?