On my old phone I had an issue with the proximity sensor and front facing camera. This led me to holding my phone backwards to take photos and being unable to hang up phone calls.
I think I put up with this for a year and a half.
I did end up figuring out the issue with the proximity sensor but opening up my phone to reconnect the camera module was too much effort for me.
Voicemail. It claimed that it was full and was actually empty for about 2 years. It’s now randomly working again, but I’ve been trained to ignore voicemail.