Finder builder/ landscaper

[dancecaller]

My daughters new house is on a hill. The site was built up and her garden is above the surroundings. The retaining wall is over head height in places.
The surveyor found settlement cracks and reccommended a structural survey, which said that the solid floor needed redoing as it had moved, also the retaining wall as the path near it had shifted.
The retaining wall was topped by a fence held together with string.
He also said that she should have her drains tested as the movement of the path might have damaged them, but when she got a man with a camera out he said they went the other way, not under the path.

She now wonders how long ago the path shifted, and if the wall is stable now.

What qualifications should she look for in people to do the 2 jobs, she doesn't want to make matters worse with a botched job.
We had a stable put up recently and were happy with the firm that did the groundworks for that - concrete base and drive. But maybe the wall is a more complicated job.