Pick n Pay no refund on ski-pants

I bought ski-pants at pick n pay Alberton City yesterday. two exactly the same size but two different colours, one fitted and one was too small. I went back today to exchange the other one. The manager said sorry we do not exchange ski-pants it's falling under the category of underwear. The ski-pant did not touch my private parts!!! The manager said he would not know about that! It came just above my knees. I told the manager to put a sign there by the ski-pants that say it is not exchangeable. I am really so disappointed. I go to that pick n pay very often.