Adobe Stock Automatic Purchase when buying the On Demand Plan

[LouiseEllul]

It is frustrating not being able to contact a real person! I've been trying to cancel my annual renewal and monthly subscription for months without being able to find my way through because the UX design for cancellation and contact support is made so complicated. In addition, Adobe Stock started an annual payment when I only wanted to purchase the on-demand plan.

How can I contact customer support for a refund?

[Abambo]

Adobe did not "start an annual payment plan", you took an annual subscription, instead of a monthly or instead of buying credit packs. You can cancel your plan anytime, by going to https://account.adobe.com, and clicking "Manage plan" for the plan you want to cancel. See here for more information: Cancel your Adobe Stock membership 

You may also contact Adobe customer care on this. Adobe customer care can be contacted by beginning a secure chat session at https://helpx.adobe.com/contact.html?rghtup=autoOpen. Pop-up blockers need to be disabled! If the chat window fails to open, or is non-responsive, use a different device to start the interaction.
Support phone numbers may be found here: https://helpx.adobe.com/contact/phone.html. Please note that phone charges may apply.

(see also here: https://community.adobe.com/t5/creative-cloud-services/how-to-contact-adobe-support/td-p/11875703 or here
https://community.adobe.com/t5/account-payment-plan/how-to-contact-adobe-support/td-p/11843852)