The security shall not be released until such time as the customs debt in respect of which it was given is extinguished or can no longer arise. Once the customs debt is extinguished or can no longer arise, the security shall be released forthwith.

Once the customs debt has been extinguished in part or may arise only in respect of part of the amount which has been secured, part of the security shall be released accordingly at the request of the person concerned, unless the amount involved does not justify such action.