Thanks for tagging me! I understand what is going on and you have already found out because it is syncing to the old Facebook account.
My suggestion is to get your user ID # and complete a contact form explaining that it is synced to an account that no longer exists. @firebombmarkus can get you the links. I am on my phone and have no access to these links. Are you aware that your game will end on King.com real soon? It only goes to level 2825 and then you can only play through Facebook but if you have a mobile device you can log into either Facebook or your King account.
When you find the ID, follow this link and fill in all the blank spaces in the support form https://soporto.king.com/contact Make sure that you are choosing the correct topic (Problems with my game) and subtopic (Game didn't save). Once you fill it in you will receive an automated email message. You need to reply to that message and explain your issue (like Elsa mentioned above). If you don't reply to that message, they won't reach you at all.