Scratchy bluetooth reception on new iPhone 5se.

Got a new phone 2 days ago. I have several bluetooth earsets. Apparently I sound good to the callers, but I can't understand them for the scratchy reception in the iPhone 5se. I think I have a defective phone. My old iPhone 4 and iPhone 5 would exhaust 2 bluetooths a day. I am on the phone a lot. This new iPhone 5se eats bluetooths just like the old iPhones I had, so I am used to that. My issue is that I have 6 Plantronics in 3 different models and I can't understand callers on any of them. Any settings that I am overlooking? Or do I have a defective iPhone 5se? The cell phone store says I need to buy an Apple bluetooth. Hah!

As a side note, I went with the 5se because I refuse to carry something that is size of an aircraft carrier everywhere I go. The old iPhone 5s I had would not get a signal at my home because of being located on a waterfront in a valley, and it would run out of battery searching for signal overnight. (No wi-fi at home) However, the new 5se shows 2 bars on the signal from my cell provider, and it will have 70% charge remaining the next morning. So that is a good thing with the 5se. The old iPhone 4 would not get a signal inside my home, but it would work outside in the driveway, but the iPhone 5s would not work at all at my home.

I also had no-signal issues on the iPhone 4 and iPhone 5s when traveling, even though my provider says this state has 100% coverage. I think that depends on the phone you have, not the cell provider.

I also carry an old Motorola SLVR that responds only to our alarm systems calls... same cell provider... but it shows a full 5 bars signal at my home... where the iPhones do not work. I carry it all the time and I can make a call anyplace in my state with it. When the iPhones don't work, the old SLVR does. The old SLVR is a far better phone than the iPhones, as far as sound quality and reception and just being a phone even though it is 12 years old. And, no, the SLVR is not paired with any bluetooths, so there is not crossover issues there.