Watch out when shopping for ostensible bargains abroad, says Andrew Smith

Shopping. Le shopping. An international language for an international pastime. Cut-price fashion? Try Tuscany's Villa Fontelugna for coach trips to the factory shops of Prada, Dolce & Gabbana and Armani. Christmas? You want Concorde to New York City for a weekend of retail frenzy at Bloomingdale's and Macy's. Cheap booze? The hypermarkets of Boulogne and Calais are the place. You can even take your euro to French branches of British supermarkets: the wine departments of Tesco and Sainsbury's are the same as those in Britain, only cheaper.

But long-distance shopping has its downside – especially if you happen to wander into a camera store called Jessops in Playa de las Americas in Tenerife. The shopfront is almost identical to those of the UK photographic chain. Apparently, that's just coincidence. There's another Jessops at Las Cucharas on the Costa Teguise in Lanzarote. Neither is the real thing. While Jessops has 210 stores in the UK, it has none in Tenerife.

Such stores promise bargain prices, but offer nothing of the sort. And most importantly of all, they have no connection to the real Jessops. So, if you need a repair under warranty, if you're just not happy with your new camera and want your money back, you have no legal right to walk into your local Jessops back in Britain and demand anything.

Jack Wilkins, of Preston, went to the Tenerife branch of Jessops in January and bought an Olympus C-1 camera. The price was £998, including some accessories that have a value of around £100. When he got home, he was horrified to discover that his local branch of Jessops sells the same basic model for £220.

Mr Wilkins wrote to complain about Jessops overcharging abroad, and was even more shocked by the reply. "The company in Tenerife has never been supplied by Jessops, and were completely unknown to us until late last year when we were alerted by a customer reporting a similar incident. We are naturally very sorry that you have been innocently duped in this way."

Jessops in Tenerife has a strange way of doing business. They offer customers a bargain, then after you've handed over payment, start to rubbish your choice. Their aim? To persuade you to part with more money for a superior camera (they say), and one which isn't a bargain. Jack Wilkins succumbed to the sales pitch. "I didn't ask whether it was Jessops – the sign on the shopfront looked so much like the real thing it never occurred to me to ask," he says.

"I thought if I'd made a mistake, I could always go back – knowing what a reputable company Jessops is," he says. The Leicester-based genuine article was generous to him: "They did give me £100 worth of vouchers – but it was quite a shock to discover the shop was nothing to do with them."

For Watchdog, we went into the Tenerife shop undercover and had an experience almost identical to that of Jack Wilkins. When we showed Jessops' chairman Tim Brookes our evidence, he was shaking with rage at the audacity of the people who opened "Jessops" in Tenerife.

Mr Brookes is now making legal moves to shut down this shop of the same name as his in Tenerife, plus two others – one in Lanzarote, another in Greece. "We have spent a fortune chasing these guys, and we are going to nail them," he says.

May Carr and her son John, from Sunderland, bought a camera from the "Jessops" in Lanzarote. "They were definitely passing themselves off as Jessops – talking about having lots of outlets," she says. Having agreed to pay £199 for a Sony camera and handed over a credit card, they were persuaded to pay £420 for a superior Samsung model instead. When they got back to Britain, the same camera was on sale at Jessops for £248.90.

Dixons also has its legal eyes on the case of a "Dixons" store in Los Cristianos in Tenerife, and has asked the Foreign Secretary to take up their case. "There were some suggestions that they were selling out-of-date models," says Dixons's company secretary, Geoffrey Budd. "But mostly it was customers being told that the guarantees were covered by Dixons in the UK, which they're not. It's immensely damaging to our reputation because customers assume we're walking away from our obligations."

In the meantime, if you're thinking of replacing your camera, the best advice seems to be to make sure you do it before you leave Britain.

Andrew Smith is editor of the BBC Consumer Unit. This story will feature on 'Watchdog', at 7pm on BBC 1, on Tuesday 26 March