Less Weight than prescribed on packet

Location/place: AFNOE, Sec 7, Dwarka, New Delhi

Name of company/service: AMUL MILK Supply

I live at above location where a Mirchmasala shop sends home delivery of 500ml AMUL milk packets. On weighing one packet was found having a weight of 320 Gms.The shopkeeper is accepting his mistake but says it distributer and the Manesar Amuk Plant who are responsible. The milk packets are sealed at Manesar Plant and distributed through Ramphal chok (M:9868063897)at Sec 7 Dwarka. Necessary action may be initiated.