Can I cancel a cruise on my credit card if the cruise line attendant told me the cruise was on a diff day?

Booking a cruise over the phone is not necessarily a rash decision. Every cruise line has cancellation policies. If you are past the final payment date for the cruise, you cannot cancel without penalty. You can try to prove that they gave you wrong information, but I doubt you will be successful.

All cruises on all cruise lines have a cancellation schedule. This means that you can cancel for any reason if the cruise is about 65 days or more in the future and get all of your money back. HOWEVER, if the cruise date is less than 60 days in the future you will only be refunded a portion of your payment, generally about one/half. In any case you need to immediately call the cruise line to make a valid cancellation. If you attempt to just stop payment on your credit card the credit card company and the cruise line will get together and determine whether it was a valid charge and also whether you cancelled in accordance with the company policy which was included in your booking information. So call the cruise line immediately. If the cruise is more than 60 days away, like in June or July this year, they will gladly cancel it and provide you a full refund on your credit card.

There is no way for you to prove that you were misinformed. None! You need to speak directly with the cruise company.