iPhone telephone calls muffled and fading

I have just replaced my iPhone XS due to people not hearing me when I make phone calls. I’m told when I make calls I sound muffled, my voice fades in and out and that unless I use the speakerphone, I’m simply not heard.

My brand new replacement phone has the same problems. I’ve changed my sim, issue remains. Many others online say they have replaced iPhones multiple tones and the issue remains. Are you one of them?

I’ve looked online and see others having the same problem, thousands in fact, and I wonder if anyone has had a satisfactory response from Apple as the the cause and solution for this issue that I understand is effecting all iPhones from 7 upwards.

i have exhausted Apple online support and Genius Bar helpers. For every Apple support guy I speak to who say they know about the issue, I speak to many others who say they are totally unaware of there even being a reported issue.

I’m thinking, if enough of us raise the issue at the same time, Apple will have. I choice but to act. so any thoughts from those in the same situation would be great.