iphone 7

I purchased a secondhand iPhone 7 for my daughter in June this year, it worked perfectly then she updated it. Surprisingly the microphone died in it. I took it to the Apple store, they told me it’s 2 years old so no longer in warranty, so we continued to use it as a text only phone. 🤔 she has recently done the iso14 update now her camera is totally black. Now she has a very expensive text only phone. My son also has a iPhone 7 and the same things are happening to his phone is there a fix for the camera at least? I can tell you right now after having an iPhone for at least 10 years I will be moving to another brand next upgrade. Not really happy!