Confused

I wanted to try on a pair of tights at the store but was told I couldn’t. I was amazed because the last time I was at a Donna store was 2018 at The Glen branch and I was buying a swimming costume. #BlackFriday. The lady that was helping me advised me to try it on because I wasn’t too sure of the size. So now I couldn’t understand why I couldn’t try on a pair of tights and the lady who was assisting failed to tell me why