GAP Pants I Bought Slackened 2-3 Sizes After One Wear

I'm not happy with what I bought at the GAP store on February 26. I bought a pair of pants for myself, among other things. To my surprise, they grew 2-3 sizes in just one day and got very loose. How could this even be? I feel like I was tricked and lied to by a brand I trusted. Even worse, the pants tore after just one day of wear, even though they weren't made to tear. This is not good enough, and I want GAP to explain why the quality is so bad. I don't have a picture of me trying on the pants in the cabin when I bought them, but I'm willing to take one now. I also want GAP to look at the camera recordings in the Cevahir AVM store, where I bought the item. The pants have grown a few sizes in just one day, so I want to exchange them for a smaller size. As a customer, I don't think this is fair, and I expect better from GAP.