Most Bluetooth pairing issues can be resolved by the following steps
Delete phone from car
Delete car from phone
Reboot phone
Restart car
Following documented pairing process
Last resort end-user has is resetting the phone and doing the aforementioned steps
If it still does not work, try using a different phone with the vehicle. If that phone also has the same issues, then take the car to the dealer and request service. You can tell them you tried all other options and strongly believe the issue is with the car.
Delete phone from car
Delete car from phone
Reboot phone
Restart car
Following documented pairing process
Last resort end-user has is resetting the phone and doing the aforementioned steps
If it still does not work, try using a different phone with the vehicle. If that phone also has the same issues, then take the car to the dealer and request service. You can tell them you tried all other options and strongly believe the issue is with the car.