Dear New Look and Asos - a problem

So a couple of weeks ago my friend Bettie had been looking at the New Look stuff on the Asos website. (I don't really understand why Asos sells this, but any how...) She noticed the price disparity between these two garments:

So the one on the left is from the Inspire range (size 16 to mostly a 28 I think although some go bigger to a 32) and the one on the right is from the Petite range (up to a size 16). And the plus size one is more than two and a half times more expensive.

You can argue that there's more material in the plus size range, and more thread, and a longer zip (if there is one), which I guess is true. But that's also true about the difference between a size 8 and a size 16, and a size 16 and a size 28, but I don't see anyone charging on a sliding scale. Besides, knowing anything about how much these garments are made for means that the difference would be pennies. There's no excuse to be charging £25 more for that difference. I guess I could accept £5 more, maybe, but not £25. 

Bettie tweeted this picture and Asos got in touch with her and asked her a few questions, which were ridiculous bearing in mind that the products were for sale on THEIR website. Anyway they said they'd look into it.

Later that day, Bettie noticed that the Petite range dress had been removed from the website entirely.

So, you'll keep the dress that rips off the fatties and makes you a nice health profit, and you'll not answer WHY the two dresses are so different in price. 

Asos and New Look, this is absolutely a problem and we're getting wise to it. 

As I write this (4th April), the Petite dress still isn't available on the website when you search for "elephant dress". I'll update this if I hear anything else before this goes live.