LPG Refills on CC Sites

Why isn't the CC in talks with a major gas supplier?  I nearly ran out of gas recently (my fault I forgot the second cylinder).  We were staying at the Littlehampton Site, and I was going to buy another from the office.  After being told the price, £29.00 for a 6 kg refill, I thought the cost had jumped up.  I have since learned that the same cylinder at Calor Depots and caravan dealers to be currently £20.75... that's a whopping 40% markup!!   Fortunately, there was more in my my existing cylinder than I thought, so we got through the week okay.... I work for the company who owns Calor and I know people who would love to set up a group deal with the CC, surely their Procurement Dept could arrange a uniform price matrix, or are they content with letting each CC Site make their own margins at the expense of its members?

Thankfully I normally buy from Calor stockists!  All I can say is avoid club site offices.. many will be inflated prices.