For a little while some of the TFSI engines were notorious for extremely high oil consumption. As far as I recall they required re-designed piston rings from Audi to solve the problem. If yours is one of those affected engines then nothing you can do by way of additives or treatments will help. Doubtless that is why the previous owner sold the car.
Sorry, but I believe you have bought a lemon.
It's the same problem that you remember from the old days from your description: pinking or pre-ignition. It's the result of too weak a fuel mixture or a spark that's too far advanced or fuel of too low an octane rating. If you are using the right grade of fuel there is a problem with the engine that needs diagnosis.
It's a common problem on Audis, and probably other brands for all I know, that the Adblue crystallises in its tank, pump, and lines leading to the lot having to be renewed.
Pinking, or pre-ignition, is not dependant on engine speed, instead it depends on engine load hence it happens when accelerating. A fuel mixture that is too weak or a spark that is too advanced will cause pinking. Modern engines normally detect that pinking and automatically adjust the ECU output accordingly.
That's not to say your engine is definitely pinking because we can not hear the sound, but it is a possibility.
68000 miles is perhaps a little earlier than expected for an alternator to expire, but not unreasonably so. Get the garage to test the battery when you change the alternator as it may have been damaged by continual discharge.
However look at another recent topic on this forum regarding "brake servo restricted" for further enlightenment.
All I hear Hamza is tyre noise. I hear nothing unusual, which is a common problem when recordings are played back. You have become mentally attuned to the sound your car makes.
Note that some tyres are much noisier than others, and affected more by the road surface. What happens if you refit the winter tyres and drive along the same stretch of road? Does the noise change or disappear?
Sorry Hamza, I will not open links to untrusted sources, however if the tyres are as bad as you describe I have no doubt they are the cause of the noise.
Heather.
There are a few companies who can repair your instrument cluster, ECU Testing being commonly mentioned here. They all require you to remove the cluster and post it to them. I forget the most recent price, but I know it was only a few hundred pounds, a fraction of the price of a new part from Audi.
Nevertheless the clutch is not opening fully. It could be a broken release bearing, a damaged release lever, a defective slave cylinder, a worn driven plate, a damaged finger, or a worn flywheel. Whatever the cause, the clutch needs to come out.