TM, it sounds like you must have had some mail go astray. They do not cut your CCB off without first sending you a letter telling you that it will be suspended in a few weeks if you don't take action. It gives you time to either get the immunisations, fill out a form, or chase a GP who hasn't registered the vax yet. If your mail is going missing, maybe getting a PO Box might be a good idea - hopefully mail would be more secure there. It would also be worth explaining to FAO and Centrelink that this has happened and try to get the payments temporarily re-instated until you can get copies of the letters again.