Solved

Engine customer choice

A manager took my engine without me being able to stop him. I don't know it and I wanted a friend of mine to have it. Besides where I see that he pays the rent of my engine, in the finances it does not appear.

Ya. Same problem here. And I'm in the same league as you. 

Unfortunately there’s no way to kick a customer. You could increase the price your charge and hope to scare that customer out. Or set very bad values (optimise cooling or reliability). But if the customer doesn’t leave, there’s no way to remove