Hi zambrsa. I am so sorry - that is an awful number of exchanges to have to complete in any time period, let alone in the course of a month. I can totally see why this is a let down.
I assure you that our number one priority is for you to have a working phone - in every single way. Since replacing the device multiple times has not fixed the issues you're having, having an Apple tech look at the phone may uncover a root problem that we are not able to see when we troubleshoot over the phone, so I am thinking that may be why our internal Apple tech representative referred you to the manufacturer directly for a diagnosis. In this regard, Apple devices are actually uniquely positioned compared to other equipment we retail, because you have the opportunity to physically work with someone who is trained to do nothing but fix your specific phone, which is a good thing. I agree that taking extra time to come by the Apple store (and believe me, I know that it can take time) isn't the most convenient outcome, but on the other hand, setting up a new phone over and over has to be exhausting in its own way!
That said, this isn't something we take lightly. Before we hit this last resort, we should be completing due diligence to walk through every possible troubleshooting flow to ensure that it's necessary. Did we already walk you through troubleshooting, including a Master reset on your iPhone?