How can I connect my phone to the Audi A6's Bluetooth system?

I recently got an Audi A6 and I'm trying to connect my phone to the car's Bluetooth system. I've followed the instructions in the manual but it doesn't seem to be working. What could I be doing wrong?

To connect your phone to the Audi A6's Bluetooth system, make sure your phone's Bluetooth is turned on and in discoverable mode. Then, go to the MMI system in your car and select 'Phone' from the menu. From there, select 'Search for new phone' and follow the prompts. If this method doesn't work, try resetting both your phone and the car's MMI system.