Certified GKH Gardening Expert
I think the first thing to do would be to call the gentleman and ask him how to remedy this. There is obviously too much of one thing or another that the plants are getting too much of. Compost is only meant to be added to the soil, not to dominate your soil. It should make up 20%, at most.
I would lightly work in some topsoil or packaged raised bed soil. You could even lift out some of the compost between the plants.