Disrespectful and condescending

Hello, I went to Mr Price at Kolonade Mall in Pretoria to do an exchange of formal pants I had bought online.

I was assisted by a young lady named Nomakhaya, to process the exchange. She then asked what's wrong with the pants, I tell her they don't zip they small. She then holds up the pants to me and zips them and says I don't see anything wrong. I then say to her Ma'am the pants are small. So then the pants had a very faint black stain of which I didn't see until then...and she asks about it. I'm like I don't know how that stain happened cause the only thing I did was to fit them when I collected them and tried them on, they didn't fit and I brought them back. She then says "Are you sure, you didn't wear them and now you are bringing them back after wearing them". Now my point is, why would I wear and come exchange pants to the other ones. Two why would I pull such stunts for pants that cost me R270???? Guys I was utterly disrespected by this statement and I definitely know if it was a white customer standing before her, she wouldn't have asked this. I won't stand such service over a mere R270 item.