So if the Formentors software is similar to my MK 4 Leon, which I think it is, then here is
how to end the call when using Apple car play.
On the digital cockpit select the right hand section and scroll to the phone details view. When connected to CarPlay and no call is in progress this says CarPlay, when a call is in progress it tells you who yhe call is with.
now during the call press the button on the steering wheel that selects the right hand section of the digital cockpit and then press it a second time. This accesses a submenu of the phone section and shows either hang up or put on hold. These can be accessed with scroll wheel.
hope that makes sense