Although paid vacations are not required by law, companies which choose to give their employee's paid vacations must adhere to whatever policy the company has in place. The company should have their policy on vacations in the employees' contracts or in an employee handbook and the company should stick with what they wrote down. Doing anything else might be considered a breach of contract.
Assuming that the company communicated a policy of paid vacations to the employees, your manager cannot go back on that policy simply because he screwed up. I believe you have grounds for some kind of suit. I suggest you consult an employment or business attorney for legal advice.
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