Many thanks for all the info
Actually I am vaguely aware of the Sale of Goods Act, but I thought you could only insist on a replacement if within a month of purchase? Probably wrong!
Also I think it all just needs calibration but the thought of being without it for nearly a month does not appeal. Do you know for sure about the Act?
Pearce,
Yes I am sure - I recently had the same issue with a Games Console and Toys 'r' Us! and went through the route I described. Initially they refused to replace, then after my letter I had a call from the store manager (Like the next day) asking me to come down and retrieve my replacement.
I had, had the console for nearly 6 Months!
The important part of the act is in bold:-
Repair
or replacement of the goods
  (1) If section 48A above applies,
the buyer may require the seller
(a) to repair the goods,
or
(b) to replace the goods.
e.g. If you "Require" a replacement, and obviously following on from that section 2), the important word is
"OR" in that Sentence, and
MUST in the same sentence! :rules:
Trading Standards could confirm. As for your statement regarding a month from repair, and I'll bet most people do not know this you actually have a right on most goods for up to 6 years from purchase in this act. Though of course the longer you have something the less likely you are to be able to make a claim. PLUS it depends on the goods itself, and how long they would be reasonably expected to last!
Again, I wish you every success on getting your kit sorted. I have to say again Jessops are normally fairly reasonable.
As a last note, people that keep referring you to Canon are incorrect IMHO. Thats because your Bean would always have to be with the place you purchased the goods from.
NOT the manufacturer as a lot of shops will try and weedle out of their responsibility by telling you.
Nuff said