Re: No great loss
Lloyd, disputes over distance consumer sales within the EU are always triable in the courts of the country in which the consumer made the purchase. You're also covered by s75 of the Consumer Credit Act: if you paid by credit card and it was more than £100, your card provider would be jointly liable for the whole purchase price less a pro-rata deduction for use of the item based on fair expected lifetime (which is anything up to six years depending on the price paid). You may have a retrospective claim against your credit card provider - often they just cough up straight away over the phone. Alternatively, principles of European consumer law are virtually identical between major western European countries, both have to follow, e.g. the Unfair Terms in Consumer Contracts Regulations, and a minimum period of two years of 'conformity to contract', i.e suitability, and often durability etc are required of consumer goods across the EU.
In reality, under accepted international norms of contract law, you were owed a warranty AND the ordinary protections of the consumer law of France and the EU (as well as the s75 protections mentioned above): indeed this is precisely what you paid for, and weren't granted. These are very simple facts you can bring to a small claims court in the UK for a fee of £20. Bring the whole story. Provide the evidence you already have, and no more. And I do believe the judge will poo all over Pixmania and grant your claim against them, which you can then have fun enforcing, either through a bailiff or other means. That's if ringing your credit card provider and telling them what happened, won't work.
All of this assumes you didn't drop/abuse the camera, of course.