This year, it was great to work with you.
On the one hand, you were super effective.
On the other hand, you have made mistakes that cost us a lot of money.
What can you offer now to compensate for the losses?
Alright, what if we give you 50% more customers to work with?
Great, we had planned to give you 100% more. What can you offer now?
These are negotiation basics: escalation.
Start low, and gradually find your way to the top.