Discussion muffled iphone 8

I purchased two iphone 8's four days ago from AT&T, the sound quality is very poor and my voice is muffled. AT&T cannot help, they advised me to go to an Apple Store. I called Apple; the earliest appointment I can get is a week from today. The representative told me she had not heard of anyone ever complaining about the sound quality on the phone, even though I had to repeat myself three times before she understood what I was saying. I also mentioned that there were pages of complaints online and that Apple has acknowledged there "could be a problem". All she would say is that "problems in technology happen with every company". Not the answer I was looking for. I have been an Apple user for a very long time and have occasionally had problems, most recently with the battery on the iphone 6 (which was replaced, but did not fix my phone problems), but my patience with Apple is running out.....

The quick fixes offered online have not helped and I certainly hope they don't try to give me a refurbished phone to replace this one.

Has anyone had this problem and were you able to resolve it?