For that matter, you should contact the customer relations or perhaps file
a consumer protection division report (complaint) where you have legal
standing; someone would look into it, eventually. You are fortunate in that
in the UK and some other locations, you can contact a different agency
whose task is to check the compliance to the letter & spirit of the Law.
{If you can be without the use if the device, you could ask if they offer a
service that involves shipping the item to a repair; they may have it. If
so, they also can return the item to you after it allegedly is repaired.}
Where I am, there is only one official Apple Store (fairly recent) in a state
that is larger than many nations. And there are no roads to most of it. 😉