I got a little worried when I read your comments about the refused cash-back so I clicked the '£50 offer' link and immediately saw the following in BOLD in the first paragraph:
Offer applies to authorised Canon dealers and may not apply to third party sellers on Amazon.co.uk's Marketplace platform. Please check with the third party seller for more information.
You say you bought the camera 'through' Amazon - does this in fact mean you bought from a third party seller and didn't check with them??? I would really like to know as I am interested in purchasing this camera from Amazon and would like to know if there's going to be an issue claiming from Canon. Thanks.