VXOC Astra-J/GTC

Ok so about a few months ago I have this really bad squeaking which sounded like it was coming from outside the car from drives side rear.
I have the discs and pads changed all round and never noticed the issue again, until the other day.

So after driving with the radio off, i can hear it again.

anybody got any idea what it could be?

A mouse

does it it happen all time? Could be pin issues or and as your pads ware down you want a dab of what's it on them