Bluetooth disconnected!

[Dazzlaa]

Hi all and thanks for looking,

I have owned an A6 avant (2016) now for approximately 6 months and one thing really bothers me more than it should. The fact that the Bluetooth will always disconnect during audio playback if a phone call comes in, or if I change service (Spotify - YouTube). Audi say I have the latest software and other forums suggest to sync the phone without contacts. This does not work for me though. Has anyone also suffered the same issue and has anyone found a solution? 
my phone is an iPhone and I’ve read that may be part of the problem?

many thanks.