This is untrue. The stock plan does not get added without you having clicked the corresponding checkmark.
Whatever plan you have taken, the conditions and the cancellation terms have been sent to you by e-mail, to remind you of the terms and conditions you did agree upon. You can always say that you did not read those terms, or that you were not aware of the consequences of checking that box, but you can't say that it got added automatically, nor can you deny getting informed about 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, 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.
Support phone numbers may be found here: https://helpx.adobe.com/contact/phone.html. Kindly note that phone charges may apply.
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.
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