On: Just pay me.

[nordsieck]

"and any leverage that you have (like a kill switch as OP had mentioned)"

A kill switch is pretty silly. All you need is "the copyright transfers on full payment for services rendered" in your contract.

[huhtenberg → nordsieck]

If they are OK with not paying you, they probably don't give a flying f#ck about the copyright either.

[larrys → huhtenberg]

So true.

Possession is 9/10th of the law.

Or as Capone put it "You can get more with a kind word and a gun than you can with a kind word alone."

[marcomonteiro → nordsieck]

+1 This is my method as well. Until the work is paid for, I own it.