Apple iPhone 11 Side Button Issue

Hello, I have been a user of Apple products for many years. I live in Turkey and I am a medical doctor. I have been using an iPhone 11 for the past 3 years. The side button (mute switch) on my iPhone has not been working for some time. When I visited the Apple store at Istanbul's Akasya Shopping Center Istanbul Turkey, they told me that this issue could be due to dust inside the device. They cleaned the device, but the problem was not resolved. They told me that this issue could not be fixed and that I need to purchase a new device. It was the first time in my life that I encountered a problem with a device, and the manufacturer said they couldn't fix it. When I asked why the button wasn't working, they said they didn't know the reason. So, I'm asking you, if there is a problem with your device, and you can't figure out the cause (clearly, it's not a user error), shouldn't your company acknowledge this mistake and provide me with a more satisfactory solution? Is it not wrong for you to pass on the cost of this device-related issue to me? Please provide me with a detailed explanation and tell me how to resolve this device-related issue. If you cannot resolve it, I believe you should take my device back and offer me a new phone as a gesture of goodwill. Best regards.