I can identify with your frustrations. I bought my 8+ on January 25th at the Apple store on the upper east side in NYC. I left the city and immediately experienced problems.
No one could hear me. People get annoyed. Are you in a closet? Where are you? are you on Mars? You sound like you are under water? You voice keeps breaking up. And on and on.
I got three phones and had the same issues with the exception of the third phone.
That was the worst. Dropped calls right and left. I could not hear conversations. Nobody could hear. me.
I spent countless hours with Apple two and three tier reps and went through hours of agonizing tests. With speaker phone. without speaker. With air pods. I had did most of the talking only landline.
I finally went to American Express and started a dispute case against Apple.
Then I got a rep who felt sorry after seeing the giant file on my case.
She got Apple to send me a 10.
I dropped the case with Amex.
I now have a 10.
No voice problems however I do not like the way the phone operates.
There is no Home button which makes it very difficult to go from one app to the next. It is also a real pain to eliminate the old apps that are cluttering up the phone.
Apple is apparently getting rid of the 10 and I don't know what comes next but I will never buy another Apple phone again.
I was really nuts by May Theend of June from dealing with the situation.
Contact your credit Card Company and try to dispute the case. Stop paying for the phone unless you already own it.
Try to get an Apple Rep who is upper level management and tell them you want to upgrade to the 10.
I know that the company is aware of the situation. They just won't admit.