Not the correct weight as stated

Bought 8kg bag only weight 7kg. Could NOT get their Facebook page or site to report this. Their contact number is disguised as 0861 PET FOOD. Tried doing a review on my finding, was not possible to submit. Seems Checkers must review selling this product. I will be notifying the store manager. Unacceptable that company's can sell something stating 8kg, but only has 7kg content. :(