poke -- you said it all --
"Were they paid? yes. on time? no."
poke, by what you said GTEM breached the contract/agreement and the other party (Uli) has the right to terminate that contract/agreement and demand the 150% payment plus all inventory and test equipment.
Also, when you said: "also if you pay a week late every time, then you are still hitting the period, just out of phase with the schedule" -- poke, can you show anything in the contract/agreement that speaks of "still hitting the period, just out of phase" and allows such deviation from the agreement?