To get you extended education trial, you need to let the system know which education provider you are affiliated with by answering the question 'how did you hear about us?' on the first page of the signup process. The answer to this question sets up the system to automatically assign the appropriate trial for you.
Unfortunately we cannot convert a regular 14 day trial to an extended education trial, but we can encourage you to sign up for another trial account so you can get the trial you qualify for.