Questionable quantity

I am a pensioner and love working in my garden. I used to buy compost and super grow from Viewpoint farming, situated in Rondebult road, Boksburg. On Wednesday I bought super grow and load it onto my 1.3 Batam bakkie. As in the past I paid for 0.7 m3. On Friday I went to Viewpoint to buy organic compost. I told the lady that I have a 1.3 Bantam bakkie and would like to buy organic compost. I used to pay for 0.7 m3. She told me that a Bantam bakkie takes a full cubic meter. I said to her that the bakkie does not take that much. She said that she will go and find out. I have asked her to bring her tape and the calculator so that we can go and measure the bakkie. A guy came in and he took the tape and the calculator and went off to the bakkie. I offered to hold the one side of the tape, but he appeared to be very irritated and ignored me. After he took the measurements, he informed me that the bakkie takes 0.8 m3. I have asked him to measure the two humps inside the bakkie where the wheels are, as that might get us to the previous measurement of 0.7 m3. He refused to do that and told me that they can`t measure each and every little hump inside the bakkie. I asked him why he can`t measure it as there are only two humps and he just have to measure the one as they are identical in size. He then said that is not the way they conduct business. I have asked him why is there a problem today, as it is not the first time that I bought compost from them and used to pay for 0.7 m3. I am more than willing to pay for what I take but don`t want to argue or fight about the quantity. I left without buying compost as I felt that he should consider the space which will not be filled with the product I pay for.