Not nice

I went to Mr Price N1 City yesterday, 17 December 2019. I wanted to return 2 items. All the staff are so friendly but there was a lady, I think she might be the manager since all the other staff asked for her help at the tills. The one item I wanted to return was not mentioned on my slip since I got it mixed up with one I had in a bag at home, but I did manage to return the one item. At first I was confused because I forgot I bought them on different dates so I asked them just to make sure otherwise I will just go check at home for the other slip. So, the lady (possible manager) then said "it is not on that slip so either it's not the right slip or you did not pay for it". She was rude and it made me feel as if she is accusing me of theft while there were people standing next to me at the tills