The Rear Windscreen wiper is stuck upright and not working.

I have changed the fuse, so it's not that.
No warning lights on dash.
I think I hear a motor whirring when I try to start it.
So how do I work out what needs fixing - trying to avoid having 2-3 costs - one for diagnosis, one for part and one for the fix..     

A3 Automatic 2014

Thank you for any time taken to reply.

Dan.

It's likely that water has got into the motor through the washer pipe and wrecked it, which was a common problem. The solution is a new motor.

I agree with cliff, most likely a seized motor. 

this happens to all audis with rear wipers at some stage

Any progress in solving this fault Dan?