Increasing nr. of high season weeks

Just wondering whether other complexes have had this happen.

Over the last few years, our management company have been decreasing the number of low season weeks on the calendar and replacing them with high season weeks making it more difficult and more expensive. This seems to be a way of screwing us without affecting the contract. There is of course no mention in the contract of how many low season weeks should be in the contract.

Anything we can do about it?