I think my iphone 7 has "loop disease" (audio call issues, headphone issues, reboot issues)

My iPhone 7 has a problem that I believe to be commonly known as "loop disease".

It started with an intermittent problem with voice calls - I couldn't hear the anything, and the person on the other end of the line could not hear me. I tried to restart my phone to attempt to solve this problem but it then did not reboot (stuck on the black screen with white apple logo). I updated my phone to rectify enable the phone to reboot (albeit very slowly) but this did not solve the voice call problem. In addition, following this update a new problem arose - I'm now unable to use the headphones. The phone does not recognise that the headphones are plugged in and when you play music the sound comes from the speaker on the phone not the headphones. Also unable to FaceTime audio call, unable to record voice memos. If I turn the phone off the only way of getting it back on again is to restore to factory settings - not ideal! I have restored as a new phone - does not solve the problem, I have restored from a backup - does not solve the problem.

Speaking to the support team they seem to think there's a problem with the audio/headphone jack. Seems like a hardware problem to me - I'm concerned that this is a known issue for Apple - how should I proceed? I don't want to buy a replacement phone.

Thanks.