My contract is 9 pages long. I leave nothing up for interpretation.

Every contract expires on Dec 31st of each year. I hand out new contracts every November to be returned by a predestined date in December. I do this every year because I also raise my fees every single year. And I make it clear that if you do not return the contract by the preset December return date your spot will be filled. This implies that the contract is not negotiable nor are the fees.