Posted: 10/04/2017 at 17:22
You say that " I had said that we wanted the old lawn removed and replaced" ... those were his instructions and I think I'm right in saying they form the basis of a verbal contract ... he is in breach of that contract ... he did not carry out the work as instructed ... do not pay him and contact Trading Standards.
I would also take dated photographs and get someone (another gardening professional would be good - perhaps someone from a GC) to look at what he's done and be prepared to speak up on your behalf.
If he wants paying he'll have to prove in a Small Claims Court that he's done what you engaged him to do in a professional manner ... he won't be able to do that. I don't think he'll bother. He sounds a lazy so and so.