The steering wheel controls on my MY14 Metropolis have always been a bit huffy with working.

The buttons for the cruise control all work perfectly. Located bottom left on wheel.
The bottoms for the trip and info etc work perfectly. Located too right on wheel.
The heated wheel control works perfectly. Located bottom right.

The phone controls don’t work. Located bottom right.
The radio mode/volume/channel controls don’t work. Located top left.

Would this be fixed with a new wheel wiring harness or is there something else at possible fault.

Amusingly this is the only fault with the car, but it’s a rather annoying one.

If it's any consolation, mine is similar in that the volume up/down controls fail to operate now and again.
There are a number of posts relating to this issue to this on the Evoque forums.
I was looking for a fix some time back and iirc one was cleaning a connector and using contact grease but it
started working again and has been generally ok since.