If 0 stars was possible that's what they would receive. After providing a "new" iPhone 6 a little over a year ago the phone suddenly stopped connecting to cellular service.
I opened multiple tickets with Apple Support, went into t mobile to test new SIM cards, spent hours of troubleshooting on my own, completely restored my phone multiple times as well as reinstalled iOS from scratch. This last effort did get the phone working. For a pathetic 2 weeks. Once it stopped connecting again, I reached out to Apple Support to reopen the ticket. Their only suggestion was to take the phone into the "genius" bar to take a look.
The "genius" that took a look at my phone ran the same old diagnostic test they always to. And didn't even allow the test to finish (saw him cancel out mid test). At that point I was essentially told I'm SOL, and my options were:
1. Buy a "new" iPhone 6 ("new" - hahaha) for, get this, $300!
2. Buy a newer iPhone
Needless to say, my next stop was t mobile to purchase a new Samsung Galaxy S8. This was an easy choice considering my work phone, a Samsung Galaxy S4 has been working without any issues at all since 2014.
I could not be happier with my switch, and already realize the superiority in the device compared to the iPhone. Apple has lost another customer, who has owned an iPhone since 2008. This will continue to happen as long as they keep 'decommissioning' old phones without notifying users. Not to mention the POS battery life on those things.
Anyway, don't bother. Get a Samsung.