If sign a contract that you will provide me a service and you back out of it midway, I'm usually worse off than if you had declined the engagement in advance. For example, if I contract you to build me a house, it takes six months, and three months in you decide to back out and pay me back with interest, I still have half a house I need to demolish or else I have to find someone who would continue your work (which I likely won't find), and I'm out 3 months' rent.
I would expect additional compensation.