Section 907. Abatement or Refund for Deficiency in Contents of Packages. – If, upon opening of any package, a deficiency in the quantity of the goods is found to exist based upon the invoice, such deficiency shall be certified, under pain of penalty for falsification or perjury, by the customs officers concerned and upon the production of proof showing that the shortage occurred before the arrival of the goods in the Philippines. Upon sufficient proof thereof, the proper abatement or refund of the duty shall be made.