Well i bought my 20d from there, it was the cheapest anywhere in the country at the time, and i got £100 rebate. The first one had a plastic spec on the focussing screen, i took it back, only 1 camera was left in stock, the display model this too had the same fault. They ordered one for me directly and it arrive in 2 days, i had an exchange. The service was excellent no argument they just swapped it, i have had trouble with exchanges and refunds at other stores saying they will do it after 30 days because that is their policy, which i find to be rubbish as they have your money and the product, and you have nothing for 30 days- rant over.
I think you are blaming jessops for something that is out of their control, its canons poor quality control standards that are to blame here i think. Do you think jessops check every canon camera box they sell?
In answer to your question i find their service superb, sure they are more expensive but isnt it a great feeling to know that you are dealing with a reputable company.
That my humble opinion anyway. Oh and if you are from uk there is a 10% discount coupon on their web business, they will refund products in store too, which is great!