Unless another method of levy is provided, to levy upon an account receivable or general intangible, the levying officer shall personally serve a copy of the writ and a notice of attachment on the account debtor.
If a levy is made by serving the account debtor and payments on the account receivable or general intangible are made to a person other than the defendant (whether pursuant to a security agreement, assignment for collection, or otherwise) and if instructed by the plaintiff, the levying officer shall personally serve a copy of the writ and a notice of attachment on such third person. Such service is a levy on any amounts owed to the defendant by such third person. (CCP 488.470)