Bluetooth Connections freeze Phone

Hi,

since iOS 9 I am plagued by the same problem, that has only gotten worse over time and up to 10.2.1.

When I have a bluetooth headset connected to my iPhone 6s (Plantronics M100 or Plantronics M90) and I am receiving a call, the first attempt to start the call mostly succeeds. But right after I hang up, then using the Button on the Headset, I can't initiate a new call. There are two possible behaviours:

1) The call seems to get startet, but gets stuck while "dialing". It's impossible to cancel the call then manually, Only after 20-30s, the phone may (or may not) cancel the attempt automatically. When hitting the number again then, the phone freezes entirely for the next minute or so. Only a reboot will break that cycle then

2) The call get's initiated, you can see the time ticking, but both ends are hearing nothing. Rest of the behaviour like in 1). As well, only a reboot fixes that until you start the next call.

I have resettet the devices, reinstalled it as a new phone, testet it with 2 different Bluetooth headphones (which both are working fine on my iPhone 6 and my Moto X, but not on the 6s).

Apple Support has run a diagnosis, with no problems being found on the bluetooth unit.

On both phones I found, that automatically connecting to any type of bluetooth device is random. Sometimes it works, sometimes not. My dated Motorola Moto x has no problems to automatically connect to all sorts of devices, so what is wrong with the iPhone or iOS??

So any ideas what the **** is going on here? Ever since I upgraded to the 6s, I noticed way more strange flaws than my 6 ever had.

Apple, are you reading this? Why on earth don't you get the wireless stuff finally sorted?

Cheers

Frank