You have two options.
1) Agree with what they do and pay more
2) Say it is a breach of contract and drop out
With 1) the company gets what they want
However with 2) the company gets what they want.
I used to work for a company that was in a similar situation. We had contracts with customers. However our cost increased in such a way that there was no way we would be able to make a profit. However the contract was in such a way that a cancel from our side would take 3 months to do the cancel (legally) so that was not an option.
The same would be for the customers. Their cancel would be three months as well. However when they contacted us and told they wanted to cancel due to the price increase, we would 'allow' the customer not to follow the letter of the law and cancel the accounts ASAP.
The intend of the increase was so customers would cancel. This so we would not loose any more money. So instead of loosing money over a 3 month period (even with the price increase), we lost money only over a 2 week (on average) period.Those who did want to follow us received a cancel letter a bit later and we had to respect the 3 months cancel.
Obviously I have no idea if they are actually loosing money or if the profit just is not high enough.