I changed from monthly to yearly suscription for the sync feature a couple of days ago (paid full pr

What can I do? I can't find any contact number or email to complain....

I suspect your title got cut off due to length, you should probably put the specifics in the body of the message. You can find the Joplin Cloud support email address in either the Terms of Use or Privacy Policy links on the Joplin Cloud login screen.