cancellation fee

The cancellation fee is for cancelling early your one-year subscription, paid on the month. It is clearly stated in the Terms&Conditions you agreed upon when you took your subscription, and is half of the remaining due. To cancel anytime without a fee, you would have needed to take the monthly subscription.

This said, if you want to negotiate a refund of your cancellation fee, this forum can't help you. You will need to contact Adobe customer care. Contrary to the advice of @Doc Maik, I strongly suggest using the chat. You will get a chat protocol, that reflects the negotiations. 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)

This is better adressed directly to Adobe support by contacting them by phone. This is primarily a user-to-user forum.