Refund disputes

I went to one of the Legit stores on Friday, I think it was five minutes before the closing time but I'm quite sure I was inside when the shop was closed. I bought a printed sweater for R120. I didn't fit the sweater on because it looked big enough to fit me and I was wrong. I got home and it was too small for me and the size was XXL of XL and they did not have a bigger size. I went there the following day to return, fortunately the sales assistant recognized me simply because I was one of the last customers to live the store, I explained to them that I have miss placed or lost my till slip. One of them called the manager on duty. Firstly she did not even greet me, I greeted her first and that said a lot about her. She refused to give me a refund because I didn't have my proof of purchase. I asked if you guys cannot do reprints because I exactly what time I was there. The sad part sales assistants were very friendly and you could see the really want to help. She insisted that I should take an item with the same value, I refused because I'm a plus size woman. I told her nothing will fit me from here. I even said I understand it's only R120 but it's still something at the end of the day. I ended up living the store without any refund because I lost my proof of payment. This happened in Promenade Legit.