Guess The Amount!

So here's yet another thing. I received a reply from Betfair today in response to my question on how I am supposed to work out what the charge will be and verify it, and it raises yet another issue. The Implied Commission they calculate on my losing bets will vary depending on the commission rate of the person (or persons) with whom I am matched!

I could be matched with 100 people. How the heck are they going to work out what rate I am to be credited with Implied Commission at?

Here's the text in full: "We calculate the Premium charge on your Commission Generated. Commission generated includes the commission paid on winnings, but also the commission that Betfair makes from the other customers who win in markets in which you've lost, which we call ‘implied commission’. When you win, Betfair collects commission at your rate of commission, but when you lose, the commission collected by Betfair from the winners is at their rate. So we'll determine the commission generated by your betting activity to be: Commission generated (Commission + Implied commission) divided by two. Implied commission is calculated on the Market losses x Average market commission rate."

It's rather like shopping at Tescos - you know the price when you pull an item off the shelf, and you know there will be an extra charge, but that charge all depends on which checkout you go to, because some checkout girls (or boys) earn more than others because they are better at their jobs and therefore you pay more for the convenience of checking out with them. The final total of your shopping bill will be visible in a few days when you get your credit card statement. All you can do before then is make a best guess based on the average cost of your shopping over the past 60 weeks. All clear?

Any legal boys ever read this? Is this practice even allowed? I would seriously be very surprised if this random element of who you are matched with affecting your charge is lawful. It just goes from bad to worse.