3. In the case of an oral notification of an ECB supervisory decision, notification of the decision shall be deemed to be served on the addressee if a member of the staff of the ECB has informed (a) the relevant natural person, in the case of a natural person or (b) an authorised receiving agent of the legal person, in the case of a legal person, of the ECB supervisory decision. In such case without undue delay after such oral notification a written copy of the ECB supervisory decision shall be provided to the addressee.