speaking of diagnosis charge, yes it is always applied, anyone doing free diagnosis is a joke because it takes time and experience to diagnose a problem.
just by reading your above problems. It can be assumed that the entire rear suspension carriage requires bushing replacement, It can also be just a frame bushing problem but that requires a good diagnosis to check. The difference in a job price can be phenomenal on a wrong or assumed fault trace.
e.g. - just replacing the frame bushings would be billed different compared to a full blown link replacement job.