Versace Sunglasses stretched.

I purchased a Versace sunglasses in November 2024 for an overseas trip. What a disappointing as the glasses got looser and looser throughout my vacation. When I returned and happened pass the store at Pavillion I asked the sales person to check it out and he said unfortunately that’s the way it is with plastic sunglasses (that are very expensive) I can’t wear them often, they are stunning but literally slide off my face. Is that normal ? Yet I also purchased a Swarovski sunglasses at the same time and it’s absolutely fine. Can I speak to a manager. My number is ***