adobe stock purchasing problem

You did purchase a plan, and you ticked the 30-day free stock offer, that you need to cancel before the end of those 30 days, if you would rather not have a full-year subscription. It's with the e-mail that came with the plan you purchased. Plans can be cancelled free of charge during the first 14 days of the paid subscription. Subsequently, you have an annual subscription plan that you can cancel at any time by paying half of the remaining due as an early termination fee. (That's all in the terms you certified having read)

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, you need to accept cookies! If the chat window fails to open, or is non-responsive, use a different device and/or browser to start the interaction.

For support via Twitter:
https://twitter.com/AdobeCare

(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)

Important: Adobe does NOT contact you unsolicited by e-mail or direct message. If you get contacted by direct message from a person, claiming to be an Adobe employee, look at that profile and look, if they bear the “Adobe Employee” marking under their name. Adobe support does not use Skype to give you support.
If in doubt, ask the forum.