Hello again.
Unfortunately, it is no longer technically possible to make purchases via Facebook Accounts for "The Settlers Online". For privacy and security reasons, purchases can only be made through Ubisoft accounts.
If you would like to continue making purchases in our game, you will need to convert your account to a Ubisoft account.
You can find instructions here.
Do you have any real examples which you can forward to me for review, or are you just assuming that? If so please feel free to send me a Private Message here.
Since the Legacy/Steam change, both I and the Support Team assisted many players. As long as you have all the requested details about the accounts there is no issue to recover it/merge.