A client is refusing to pay invoices in full, stating that they will deduct "costs incurred" in switching to a new IT provider.

A client of several months is refusing to pay about $3,000 worth of invoices (parts, equipment, mostly labor). They had managed to haggle previous invoices down, but when I refused to budge on this one, and refused to do further work, they said that I was going to be held responsible for "economic hardship", costs of switching to a new provider, etc., and that those costs would be "deducted" from the final check. We have no contract, work was performed on a "break/fix" basis. Things are fairly well documented in email and text messages. They aren''t saying the work was bad, but are saying that I shouldn''t bill for all time on site, just "active" time. (Crazy!) 1) Can I press "theft of services" charges? I don''t want to, but I do want to get paid, and they''re now threatening me with bogus hacking charges so it might give me some leverage? 2) Can I put a lien against all the equipment I worked on, and possibly repossess the equipment not paid for?