What action can i take for selling of under weight cylinders

I have seen many delivery boys cutting gas from LPG cylinders in their delivery auto, we cannot take proper videos as they have covered autos where in they perform such malpractices, these delivery boys are making huge lot of money and are not worried about the complaints ,,,, please let me know proper department where we can complain it to the highest most level and actions are initiated urgently. Please let us know all such departments along with the officers mobile number and email ids where we can lodge proper complaints, no such police department takes action till date even if complaint