DACS

Re-linking an account

DACS identifies you by the pair (issuer, subject) the identity provider asserts — never by your email address. That is what stops someone who can persuade any provider to claim your address from inheriting your account.

Why you might be locked out

The subject is an opaque identifier the provider generates. If the identity provider is rebuilt from empty, or your account there is deleted and recreated, you get a new subject — and DACS correctly treats that as a different person, even though your email and password are unchanged.

This is not something you can fix by trying again, and it is not a sign that anything was compromised.

How it is fixed

Re-linking changes the security identity attached to an existing account. It is deliberately an operator recovery ceremony, not a browser button: a self-service version would be a way to take over an account.

An operator proves the new provider identifier through the provider's own administrative surface. A matching email address is not evidence.
Active owners authorize the change. With two or more owners, two owner identities are recorded; sole-owner recovery is marked explicitly as the weaker ceremony.
The operation revokes the account's live sessions, writes an immutable recovery record, and appends a hash-chained ledger event in the same transaction.

DACS will never link two accounts because they share an email address. If you are told an account already exists for your address, that is this rule working, not a fault.