Lays under weight

I purchased the 120g bag of lays from the checkers near me and when I was packing it away, I felt the bag rather empty. I decided to place it on my kitchen scale and the weight read 86g. I then placed another sealed bag on the scale and that was 118g. I mailed them on *** with this for the first time on the 12 May and received no feedback. I again about 3 weeks later send through a comment from their website assuming someone will respond and again nothing. I think their customer service is extremely poor.