Glad you're on the way to getting it sorted 🙂 not going to lie they're expensive cars to maintain. Spent £1k on mine last month alone. But theyre fantastic abd strong cars.
If cold and hot air is blowing then there could be an issue with the control unit. Yu could get a diagnostic check carried out to see if any fault codes flag up. Did you buy from a dealer? If so , abd within 30 days of purchase I'd take it back to them to look at as you have 30 days to return the vehicle for a full refund.
If it were me I'd leave it for a garage to sort but I'm.not most mechanically minded. You could also consider a diagnostic check to see if any fault codes flag up regarding the system
I'd also argue, that by them agreeing to foot 75% of the bill, they agree with your opinion that the frame is the issue. Therefore in a way they're admitting they haven't repaired it.
If it's been back whilst under warranty then you should be covered as the issue still hasn't been repaired. Might be worth you speaking to Audi customer care too.
Can't go wrong with an induction kit, sports exhaust and remap. Think you'll be looking at a touchscreen type head unit so expect to pay at least £300 I think.
To find the interior colour they'll be a sticker in the boot floor on the edge of the wheel well. Once you know what colour your interior is, my advice would be to look through eBay, at cars being broken for spares.
Funnily enough this came up on the a6 c5 forum a while back. Might be worth you measuring conventional mattresses to see if any fit. I'm sure you'd find one as the q7 has a very large and flat boot area.
Unless your car specifically requires it then I think you'll find no or hardly want change. Plus any benefits are often out weighed by the purchase cost.
As you've changed the battery, have you checked it's holding charge or that's no battery drain on the car.
Also is it worth having an auto electrician check the wiring loom for any loose connections or frade wires etc.
If I remember correctly the a1 vents are the same as the a3 round vents and as you say it's hard to clip anything to them. I wonder if there's anything universal out there that stocks to the dash.