Contractor help paid cash now screwed

[Dee Schwarts]

Recently purchased a house and needed basement done.  Contractor says we owe 6k in addition to the 26k we already paid with cashiers checks for installing a door where an arch was, fixing a shower, fixing a bathtub, wiring a hot tub.  I realize it is arguable the market rate for these things and quite possible that the work is worth 6k (which is more than I would have wanted to pay) We paid the original 26k to have some framing, plumbing, electrical work done, and again it wasn't exactly clear what were paying for.  Yes I already know we are dumbasses you don't have to tell me again.  What I want to know is if the contractor puts a lien on the property if he was crooked could he say we didn't pay the 26k that we paid with cashiers checks plus the 6k?  Now if he does put a lien what recourse do we have being that we don't have any written contracts?  If he isn't licensed and didn't pull permits is there any way we can retaliate by reporting him to the city?  Also he bought some of the materials under his own name, so if we decide to cut him off (which I'd like to do) he could always say "well these are mine" and say we stole them is that correct?  Please advise.  Thanks.