Aaaargh, that is SO misleading, confusing and probably contravenes an ASA rule or two!
Apparently not. According to the ASA, it's perfectly OK for a web site to display misleading information when selling a product, provided that it only reproduces an exact photograph of the product packaging, even if it's total nonsense.
I complained about something else very similar and got this reply:
The material you complained about is not covered by the Advertising Rules. Please see below for further information.
The material is out of our remit because ASA isn’t entitled to regulate claims on ‘packaging’ or the actual goods/products themselves, unless they refer to promotions such as free offers and prize competitions. For these reasons, we have not assessed the material and we will not be taking your complaint further.
Trading standards would probably have taken a very different view, but trading standards does not have a simple email address to lodge a complaint to and get an adjudication.