Id start by clearing out the old phones
Turn ignition off.
Press and hold the pairing button in the centre console with the picture of the face, NOT the button on the wheel with the same icon.
After 5 seconds turn on the ignition to the accessory position.
Continue holding the pairing button for a few seconds.
Release the pairing button.
'Bluetooth Pairing' should now be displayed on the radio or Nav screen.
then hold the same button for 10 seconds itll beep to say there cleared. then do the above and find the BMW on phone and add with correct pass key