I've been having the same issues. I can't remember my password and I've been trying to reset it for ages in order to pay my bills. For a while, I gave up on it and I was paying them through the phone but now you guys changed the way we pay through the phone so I have no idea how I'm supposed to pay you.
It asks me for security details, which I enter. then it takes me to the next screen where I see the New password and Confirm password text boxes. After I fill them both and press change password it kinda refreshes the page and says that some information is missing as it does for the user above me.
I can then re-enter the new password and press the button again however this time no information is missing but my password also doesn't change it just takes me to the start of the change your password form.
I am having the exact same issues as the other people in the comments, password meets criteria, all information is correct and then it says Some information is missing or incorrectly entered. Please check below and try again. I have tried multiple times.