Received less material than purchased - measure/count all material

I bought 12m2 laminate flooring along with the underlay. I had a delivery person fetch the material and while they counted the boxes we didn't think to measure the underlay . 2 weeks later I'm getting the flooring installed only to find that I had only be given 6m2 underlay. I honestly trusted that a big company like CTM would have better controls in ensuring that customers are not cheated. Had to go back to the same shop to buy another 6m2 and even though I was given a discount the fact is that I paid for material twice. Just placing this review to warn CTM customer to count all materials even if it means carrying a measuring tape to measure length.