I've had the same problem when researching. My advice would be to speak to Audi parts department. If you give them the wheel part number, I'm sure they'll be able to give you the airbag number.
Cheers
Steve
I wouldn't be letting this go as it sounds like the garage haven't resolved the issues at all. If you're not getting anywhere you could always contact the Motoring ombudsman.
Cheers
Steve
You'd need a multimeter to check the electrical supply to the speaker. Have you checked the wiring from the sensors to the buzzer a d reverse lights?
Cheers
Steve
On a plus point it's better you're buying from a main dealer than private garage or individual. The mileage is a concern but Audi approved used like all approved used cars are often cream if the crop.
Audi should be able to tell you if the car was fleet/business or private use. And as long as it's well serviced I can't see there being too much of an issue.
For added piece of mind you could always take out an Audi warranty as long as it covers everything like the normal 3 year warranty.
Cheers
Steve
This thread might help:
https://www.audi-sport.net/xf/threads/meyle-hd-kit-anyone-had-an-early-failures.226201/
What made you decide to change to MeyleHD?
cheers
Steve