In this case the Audi dealer may have been correct. No doubt they fully expected the customer to have them do the job. They might be expensive but the guy did buy an Audi, cheap they 'aint.
Why did the fast fit not confirm the diagnosis?
Probably because they had no idea how and/or no equipment to do it.

how could they be correct if fitting both sensors did not work? , thats just lazy. and why should the fact he has an audi mean he should f###ed around by tits with as much talent as a monkey