'27' has the story they gave me when I complained about the sign by the customer service desk other retailers selling on to customers - I had gone to complain about length of queues when some checkouts were shut, and threw this in for good measure.
I said I often buy a week's load of 10p (now 6p I see) strawberry yogurts - of which I often nibble two per day - with no problems. They say the checkout people have discretion.
They also have a limit of ONE mobile phone per customer, and there was a student-with-not-good-English ahead who chose a phone, wanted one for her and one for someone else and couldn't understand the concept of two phones being in the rack, which she couldn't buy: Customer service were telling her to come back in an hour! sigh
Write politely to [email protected] (he's the Chief Exec): obviously he doesn't see the emails himself but it goes a bit further up the chain.