Bluetooth disconnects from car

I'm having problems with my Bluetooth car connection.

It's perfectly paired and working fine, but 3 out of 5 calls it disconnects during the call.

I was hoping this will improve with th iOS10, but it hasn't.

I've tried deleting and re-pairing the phone to the car many times, even deleting all paired phones, and hasn't worked.

By the way my car is a 2008 Jeep Grand Cherokee.

I hope I can get help in resolving this issue.