There was a slug/insect in my Bikaji Bhel-puri pack

So, I was out with my friends in a nearby garden for a picnic where I opened this packet of Bikaji Mobile bhel and there was this quite large slug in it. Evidently he had access to the packet containing the bhelpuri top as its stains can be seen at the places it must have crawled to. Coming to the point, I want to ask the community what measures should I take to ensure that the Bikaji company learns about this and takes some necessary action. Should I just e-mail them or should approach the store from where I bought it or is there any other more efficient approach?