Confronting people

Today I returned an item to a store. I have been shopping there for 18 years. This is the first time I returned something. The cashier told me that she will not take it back as it is a few days past the 21 days. I told her that the sales lady said 30 days. Anyway, I left and then phoned the manager and said how disappointed I was. She was quite dismissive. I ended up writing a negative review and decided that I will never go back there again. I felt so awful after the experience that I had some wine. My question is, should I have just accepted that their policy is 21 days and said nothing and then I would have not felt so awful confronting them?