Horrible Reception and Customer Service/Support

I currently have 2 Samsung Galaxy S8 phones. They were purchased on June 13th 2017 from a local retailer. I have had nothing but problems with the reception on these phone at my house, office and in other locations. I called in on the 15th of June and reported it and was told that I need to utilize WiFi calling and report it on some app called MARK THE SPOT. Other then that it was what it was. My problem with that is I'm paying for WiFi separate and shouldn't have to base my cellular coverage off it. In the event of a emergency and my WiFi/Internet is down I can't make a reliable call. Also most of the reviews for the app MARK THE SPOT state that it is a waste of time and nothing even gets done. I had Samsung S5 phones before and the coverage was bad but has only gotten worse. I was never told I better use the "Buyers Remorse" option before this would become a nightmare. Even though the "Buyers Remorse" would cost me another $45.00 per phone to utilize. I also called in on the 15th and now the 28th of June about this issue.
Second I have also had one of the phones that got a crack in the back glass cover (no it wasn't dropped) and called in on the 17th about it. Was told that once the crack was in there it voids warranties and I would have to have had insurance and pay a $200.00 copay. I just paid $750.00 for a phone and now am suppose to pay $200.00 more for a crack that wasn't the result of abuse. But try explaining that. I took the phone to a repair place and had the back fixed. Today the phone has developed another crack (sitting on my lap in my car and have 2 people that can verify) so I talked to the repair place about it. He said more then likely something is expanding (like the battery when charging) and causing the cracks. I am told by AT&T there is nothing that can be done through them and I would have to send my phone into Samsung to get it fixed. At first I would have to go without a phone and then after 2 hours they said they would send a loaner phone for the one that wasn't cracked. One of the options for the phone with the crack and the original complaint of horrible reception is buy a new phone. Take the cracked back cover out of the complaint I called and reported reception problems on the 15th but I am told still to us WiFi calling. I have had my wife ask other people on Facebook about their coverage out in my area and almost all responses were very negative. I am highly disappointed in my customer service/Technical support and hope this goes somewhere. I was transferred to probably 5 people, hung up on twice and never got anything accomplished. AT&T is happy to sell you the phone but wants to blame everybody else about the problems. No accountability. Just as a reminder I purchased the phone on June 13th, called in on the 15th, 17th, and the 28th. At this point 90 for BUYERS REMORSE would have be a great idea. I guess I'm a day late, 90 dollars short.