my experience of jessops staff is also completely useless - but then it's not their business, they're mostly just teenagers or whatever doing a saturday job so they don't care about you, photography or giving you a deal.
i remember asking about a CF card, i was told something along the lines that CF cards are for older cameras and they don't stock many, and the only one they did have was like 80 quid - i did ask if that was the 'best' price they could do, having seen the exact same one on 7dayshop for less than £30.... they wouldn't budge.
... and like you, they've lost all my business now, but it's not as though they stock much that's generally useful anyway, my local branch doesn't even carry the 70-200 f4 anymore, just a couple of random tamrons.