Mfsw Button Problem

[Lyons]

My wife reported this morning that the phone button (that answers/ends calls) on the mfsw of her Mk6 hasn't been working recently.

All other buttons are operating as normal, it's just this 1 that isn't.

The wheel was factory fitted and the car is under warranty, but I just wondered if there's something simple she's done to turn it off before I contact the dealer.