My bank/credit union cashed a post-dated check even though I told them about the post-dated check before they received it. What can I do?

If you only gave an oral notice, without confirming it in writing, your notice is only valid for 14 days. After that, the bank or credit union can cash the check before the date you wrote on it. If your bank or credit union cashed a check before the date you put on it while your notice was still valid, then it may be liable to you for any damages.