Not satisfied with product

About a month ago I bought Nestl?'s Hot Chocolate (1kg) and discovered that ii was way less ( not even half) filled with its contents. So I logged a complaint and spoke to a very friendly , apologetic Jackie (all the credit to her for the service) that listened to my complaint, took all my details and said that she will send me vouchers to make up for their mistake and also promised to chat to their manufacturers about that. Needless to say I haven't received any vouchers for their mistake. Again, yesterday I bought another Hot Chocolate and discovered exactly the same- the container was not even half full. Unfortunately I really like this product otherwise I would just have to change to another product