I suspect you're right, at least if my own experience and that of several others is anything to go by.
If I were you I'd hound the salesman until he's sick of the sound of your voice, and when you aren't doing that, get on to Audi UK Customer Services and make sure they know too.
Have you looked in your manual to see if it says you can adjust the subwoofer in a car that has one? It may be different in the latest edition. If it isn't different, your case (and everybody else's is stronger). You paid for ***, remember...
The only way this will get sorted is if enough people complain about it, but the complaint has to go to Audi UK. The dealerships won't escalate it voluntarily - all that'll happen is you'll be told that's the way it is, like it or lump it.
And that won't do.
Agreed, I'll start kicking off on Monday. Either way we need an official answer, as Ambroos' point could well be valid here.
I had *** in my A1, and the sub was in the wheel well, nice and secure as there was no space saver. My other thought is that the s3 sportback sub is in the spare wheel and can be removed for access, so I wonder if they've disabled control as any further power/bass into it could well cause rattles or distortion from the *** equipment. Not sure if that argument holds ground if b&o sub is in the same position.