In US its called the lemon law, in UK its just "goods not fit for purpose". I guess it would take multiple people threatening to take the car back under these laws for them to take any notice. The car was sold with the claim of ability to control climate remotely.
I believe this is a recurrent problem on frosty mornings , everyone wants to defrost their car at the same time.
The Audi server is obviously not capable of coping with the extra demand.
This is no excuse though Tesla apps work perfectly in similar situations.