iPhone 7 Plus Calls + FaceTimes Keep Failing

I have had an iPhone 7 Plus since June 2017. Have had minor glitch issues but usually no problem. Then all of a sudden for the past few months my calls and my facetimes fail even with wifi. Especially facetime will immediately fail. or if my phone call goes through, the speaker button is greyed out and I cannot hear anything at all. Also sometimes my wifi button will be greyed out too. I have taken the SIM out and put it back in, reset network settings, even factory reset my phone. I have seen others with this issue too and it’s really frustrating. You buy an iPhone to last and then they ultimately screw you over into getting another one. How can I fix my phone without giving into Apple’s dumb antics and buying a new one?