I have been doing this, but it just reverts to a booming volume next time there is a travel bulletin
I have found volume settings for when the parking sensors are in use, iPod volume input - but can't find one or the damned traffic announcements. The 310 instructions say "During a traffic announcement, the traffic announcement volume setting can be adjusted with the volume control. The adjusted settings will be applied to subsequent announcements." But this is not the case with mine unfortunately.
Unless someone on the Forum has a wondercure, I think this will be a warranty job. And then the fasting and praying that collateral damage is not done.
I know this is fate telling me to buy an upgraded head unit, but I want it to look plain so as not to appeal to villains. I was amazed to hear from a friend of mine that people stole his wing mirrors on his old Audi S3 as they were stainless effect. This happened more than once and damage done led to him losing his no claims bonus. Given that my camper will be staying in all manner of unknown locations, I want to keep it low key.