iPhone 7 no service

My son has an iPhone 7 Plus and I have a iPhone 7. Both phones are replacement phones due to poor service. Both phones worked flawlessly and almost simultaneously both phones now have service issues just like our iPhone 6’s did. When talking on the phone we can hear everything clear as can be but the person that we are speaking to can not hear us. I have called customer service more than a handful of times to get the run around, I have driven to the actual store that is 14 miles one way from my home to be sold two new SIM cards that did absolutely nothing. Now I’m being told that I need to do another insurance claim and purchase two iPhone 8’s? Any help would be wonderful before I change phone services.