If bought within 30 days from dealer you are entitled to a full refund. Or for them to fix it. What's the service history on the car? Has the gearbox oil been changed on time etc.
Madness. Let me just add, you might find it's not genuine leather but instead a plastic substitute. Vegan leather is also a name for it. Hopefully it's real leather though.
There are different types. It's the back contacts that are most important as they have to match. You could try a vin decoder as it should give you the options list on your car which might help narrow down which one.
Alternatively there should be a part number on the cradle. If you speak to Audi parts department they should be able to advise which phone matches the cradle.
I don't blame you, it's definitely a case of passing the buck. Technically if the car isn't fit for purpose then it is the finance companies responsibility.
Seatbelt warning light could be a loose wire under the passenger seat. A diagnostic check might give you more info.
Just take the car to an exhaust garage. As it could be the hanger instead of the centre box.
Do all electrical items work? AC compressors can be expensive to replace if it's not working. Also if it's like the A6 of the era I wouldn't be surprised if it's hard on suspension arms. I'm assuming it's full service history?
If xenon headlights make sure these are working as theyre expensive to change/fix
Why is the owner selling it?