Front and rear camera not working after update

So i updated to ios 14.7.1 first snapchat started jamming then rear camera and flash stopped working on any app and the actual iphone camera app front (selfie) works on the camera and snap but neither work on instagram or watsapp. Done everything apple recommended even went to apple store where they said its a rear camera hardware issue sensors have failed the staff member even did a factory reset but how can they fail but work on certain things and have quoted me £75 to replace rear camera im addament its the update otherwise front wouldnt work at all not pick and choose which app to work in.