Audi A3 rear suspension issue

Bought a second hand 2011 Audi a3 last year.

When there is someone in the back and I go over a speed bump or turn very sharply there is an unmerciful squeal from the back of the car.

I recently had the car serviced and I told the mechanic about the noise, he took the car for drive (with some weight in the back) and heard it too.

He told me as a suspension sytem is made up of so many elements that it is impossible to pin point where the noise is originating from.

I said so where do I go from here then?

He said... well the only way would be to start replacing things one by one and test it after each one, first the shocks and then the bushings, but it could be elsewhere so if it was him he would just leave it - as on visual inspection he sees no issues.

Surely there is a better answer then what he gave me / way to pin point the sourse of the noise? I've read thru forums with similar issues and most say it was the bushings, is replacing these a big job?

Any input welcome.

Thanks