In-car Bluetooth music playback stopped working

Hello,

Apologies if this is the wrong place to post this but I'm struggling to find my way around the support community categories.

I am having trouble playing music in my car via bluetooth on my iPhone 6 (v8.3 of iOS). I have a Volkswagen with an RCD 510 stereo and I have happily been playing music via bluetooth on this for months. I was also able to control the music playback via the touchscreen on the car stereo. Last week the music playback stopped working.

The mobile phone portion of the connection is working correctly and I can make and receive calls without any issue. However music playback has stopped working. I can still see the track that the phone is playing displayed on the stereo with the time remaining on the track at the point of playback displayed correctly, the stereo is also showing the track as playing (as opposed to paused) but no sound is coming from the speakers. The time remaining shown on the car stereo doesn't decrease either, although on the phone I can see that the track is playing as expected. I can then press play on the car stereo and the track plays on the phone but again with no sound, pausing the track on the car stereo doesn't work and it carries on playing on the phone.

I have tried connecting an iPad and iPhone 5 to the car stereo and these work perfectly. I have tried connecting my iPhone 6 to a portable speaker via bluetooth and this works perfectly as well. I have also tried the following fixes to no avail:

- Playing music through Spotify, Downcast and the native music player on the phone

- Deleting the bluetooth connection to the car on the phone and reconnecting

- Deleting the bluetooth connection to the phone from the car and reconnecting

- Switching bluetooth off and on again on the phone

- Switching the phone off and on again (by holding down the lock button)

- Rebooting the phone (by holding down the lock button and home button at the same time)

- Resetting the network settings on the phone

- Various combinations of the above

- Banging my head repeatedly on the steering wheel in frustration

I've run out of ideas now, I don't understand how the car and phone can play nicely with other devices but not each other, nor how the mobile calling and track display portions of the connection work but the audio doesn't.

Any help with this would be much appreciated.

Cheers,

Matt