I am sorry when we spoke I didn't write down the correct password. Can you call me to give me your password again or you can email it to me in a separate email.
I imagine that the person you spoke to told you the correct password. I guess the error was in the way you wrote it down, so you should say, 'I'm sorry, but when we spoke, I must have written the password incorrectly, because it doesn't work. Please call me again or email it.'
This is a polite way to assume the information was given correctly, and that you made the error. It's also possible the caller gave the wrong information to you.