On July 20, 1938, one Lucas Resurreccion delivered to Aurelio de Luna, inspector of a truck belonging to the petitioner, Raymundo Transportation Co., Inc., a package for delivery to the respondent W. C. Olitan at the company's office in Manila with the amount of 10 centavos to cover the freight charge therefor. The inspector, upon noticing that the package was addressed to W. C. Olitan, refused to accept it. Thereafter, respondent wrote a letter to the company's manager and complained of the incident, to which said manager replied justifying the inspector's refusal to accept the package, for the reason, among others, that respondent W. C. Olitan was an enemy of the company. Whereupon, respondent Olitan filed a complaint before the Public Service Commission, and after due hearing, a decision was rendered wherein the petitioner was fined P10, with a warning that a severer penalty would be imposed upon it in case of repetition of the same offense. Hence, this petition for review.

Petitioner maintains that there is nothing in its certificate of public convenience which requires it to render the service complained of, nor is there any law, order or regulation of the Commission punishing the act. Petitioner's certificate of public convenience was issued subject to the following condition:

"Que la compania solicitante Raymundo Transportation Company, operara al servicio del publico para el transporte de pasajeros y carga,  * * *"  (underscore ours) and, to this effect, tariff schedule for passengers and freight was also prescribed therein. It is, therefore, obvious that petitioner, in refusing to accept the package, violated one of the conditions imposed by its certificate of public convenience, and to the extent that the refusal constitutes an unjust discrimination against respondent, it was also a violation of section 18-(b) of Commonwealth Act No. 146 thereby subjecting it to the penal provision of section 21 of the same Act.

Under the provisions of the Public Service Act, the Public Service Commission has general supervision over all public utilities and the power to investigate, upon its own initiative or a complaint in writing, any just cause of grievance against any of them, to make and enforce reasonable rules and regulations, and to provide for and grant relief in all proper cases.  (Philippine Shipowner's Association vs. Cui, 48 Phil., 377.)

Judgment is affirmed, with costs against petitioner.

Avancena, C. J., Villa-Real, Imperial, Diaz, Laurel, and Concepcion, JJ., concur.