Wouldn't matter if they did. Unless you agree to the pay cut, you're getting the written amount. If they insist it's supposed to be 24k, stay quiet on it. Especially if they ask what you were offered. They can't force you to tell them, and the right to silence is one of those that you get regardless of who you are or where you're from.

If they try to change your wage, or fire you for not accepting the correction, that would be breach of contract or at least wrongful termination at least.... and that turns into a sizable settlement.