Apple iPhone 11 Freezing Issue

Yesterday, I bought an iPhone 11 for my daughter. She signed up for iCloud, opened the phone, and started exploring the apps right beside me. But within just one hour, the phone got stuck on notifications and froze. No matter what we tried, it wouldn't respond, shut down, or access any other features. Still at the mall, we rushed back to the store where we purchased it, but they couldn't do anything. They told me to call the support team, and if that didn't work, they would send it to the technical service. It was Friday evening, and the support team gave me an appointment for Monday. If the issue isn't resolved by then, we'll be leaving for a month-long trip with my daughter, who has no phone now due to her previous one breaking down. I'm extremely disappointed. This newly purchased phone, for which I paid four times more than other models, shouldn't malfunction like this. This is beyond absurd. I've been an Apple user for eight years, with all my devices being Apple products, but this time it's a letdown. My daughter cried yesterday.