For starters, I suggest you click on Report to ask a Moderator to edit out the personal bits of your post. All you can do to solve this problem is by telephone with your ISP and if they won't accept that you don't have the right information, simply stop paying them and go elsewhere. Once they're faced with that, they might play ball with you.
They should tell you he security question and ask you for the answer. If you don't know that, they would safely assume you aren't the account holder.