This is a bug many site or apps have. You should try doing forget password. If it still doesn't work try contacting TWC and tell them your problem so they can help you and fix this bug permanently. To secure your account we likely to choose complicated passwords but we often find ourselves forgetting or mistyping the password. You can search online to know how to reset your password for not so simple things for example you can search how to reset a forgotten apple id password, in case you forgot your apple id password.