Before cancelling a contract, the Department will give 30 days' written notice of its intent to cancel to the contract holder and to any junior lienholders for whom it has given its written consent to encumber. The notice shall be given by certified or registered mail, return-receipt requested, or by first-class mail, or by personal service, as deemed appropriate by the Department, to or at the last known address of contract holder or junior lienholder as shown in the Department's contract file. The contract holder and all junior lienholders are responsible for keeping the Department informed by actual written notice to the Department of the proper address to which notices are to be sent. The notice shall be effective upon mailing, or upon actual service if given by personal service, and the default must be cured within 30 days thereafter to avoid cancellation.