Had issues with builder and engineer. Now discovered that they did not dispose of garden shed roof properly as requested, but used it as infill for foundations - the building works were a huge job, and I specifically requested that the builder dispose of asbestos roof correctly - small roof - 10 by 12. Where do I stand with this? Can the builder be prosecuted for this? We only discovered it after drilling down a part of the foundations. This leads on to the issue also that the foundations were not done as originally specified by the engineer, but I understand from new engineer, that they are satisfactory. Any comment/advice?