You need to slow down a couple of minutes.

I don't think you know what you have yet. All you have told us is "The Client Says".

My recollection from and old business law class is that you can not have a "Verbal Contract" for certain transactions, and I believe one of them was transactions involving real estate.

If they don't have a written, properly signed enforceable contract - they don't have a sale yet.

GET THE PAPERWORK. If there is none, then they have no sale yet!, 

If there is paperwork, then you can figure out how to proceed.