Unknowingly got locked into an Adobe annual plan?

You already had a monthly plan. All the Photography plans, and the Student plans, are annual plans - in exchange for the huge discount. By contrast, Photoshop alone, month by month, is $30+ per month. Similarly the all apps monthly plan is $70-$80 per month. 

contact adobe support and explain the situation. there are 3 ways to contact adobe; chat, phone and twitter:

chat:
use a browser that allows popups and cookies
and click here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
in the chat field (lower right), type AGENT
be patient, it can take quite a while to reach a human.

phone:
https://helpx.adobe.com/contact/phone.html

twitter:
tweet @AdobeCare

p.s. if you're contacted by anyone (via email or private message), it's much more likely to be a scammer than an adobe representative. ie, double check for an employee badge if contacted in the forums and look for an adobe.com domain in the email address if you click reply to an email. then check again and be very suspicious. any other method of contacting (or offering to contact you) is almost certainly a scam, https://community.adobe.com/t5/using-the-community-discussions/staying-safe-in-the-adobe-support-community/td-p/12919684/redirect_from_archived_page/true

Moved to Account, Payment, & Plan forum,  from the Photoshop forum.

We can't help you with payment issues on this forum, you need to sort it out with Adobe - if you've only just subscribed you should be able to cancel your subscription. There's a reduced   subscription plans available for students - it would be worth you seeing if you qualify.