Media: 'Ad guerrillas' Tango with PR disaster: Companies are waging war with bold and bizarre stunts to put their message across, reports Meg Carter

Advertisers are growing desperate. Increased competition for attention is making it more difficult for adverts to stand out from the crowd, and agencies are trying harder than ever to make an impact. But the recent experience of the drinks manufacturer Britvic offers a cautionary tale few can afford to ignore.

Ringing doorbells and running away. That's how the Independent Television Commission recently described the commercial for Britvic's 'Tango Still', upholding 63 viewers' complaints that the ad misled viewers into thinking the product was bogus.

In the commercial, a man identified as Tango's marketing director warns that the company makes only fizzy drinks and that a product called Still Tango is now available. Still Tango is an unfranchised product, the ad claims. Anyone seeing the drink on sale should ring the company immediately. Some 300,000 viewers did - only to be told: 'You've been Tango-d'

The ad has raised questions about advertising industry ethics. The ITC has warned agencies not to 'cry wolf' in TV ads. It says it is concerned that campaigns playing on the authority of television devalue it as a medium and that Tango and its ad agency, Howell Henry Chaldecott Lury, were guilty of 'trespassing on public confidence'. The commercial has now been withdrawn.

But HHCL's approach has found favour within the advertising industry. Its bold and irreverent stunt is the kind of tactic that makes a product stand out in an increasingly cluttered media environment, says Trevor Beattie, creative director of advertising agency TBWA.

'What Tango is doing is great. It is expanding advertising beyond just a piece of film. You've got to get your message over,' he says. 'The ITC has expressed concern about all the recent Tango commercials. But I'm sure this latest one will prove to have worked as well as the others.'

Tango is only one of a growing number of advertisers pushing the limits in an attempt to grab consumers' attention through a variety of spoofs, stunts and gimmicks - an approach known as 'guerrilla tactics'.

'It has always been desirable to create the idea that your advertising means something beyond the ad on the box, that it has some wider significance,' says HHCL account director Dominic Field. 'You can generate huge PR around it if you can create something to generate maximum impact.'

In one stunt, Saatchi & Saatchi created a 'live' cinema commercial for British Airways' romantic weekend breaks. When this was shown at a West End cinema, an actress hiding in the audience recognised her 'boyfriend' in the ad on holiday with another woman. She rose to her feet and shouted at the screen; he turned to camera and answered her back.

In another stunt, TBWA threw a Nissan Sunny out of an aeroplane. And when WCRS launched the Sega Mega CD it created a campaign that aped tactics long used by many activists and political groups to hijack its own ads. A TV commercial was 'disrupted' by a pirate TV station, poster sites were attacked with 'unauthorised' stickers.

Such guerrilla tactics were once the domain of small advertisers with little cash. A clever stunt can attract media attention worth thousands of pounds. At last year's Daily Mail Ideal Home Exhibition, the homeless charity Shelter parked a mobile poster van outside the London venue. The organisers banned - and removed - the van and the stunt generated national media coverage.

But bigger advertisers are recognising the value of this approach. 'More campaigns now use these tactics as it is harder to reach certain consumers through traditional media,' says Peter Cowie, client services director at WCRS, the ad agency that handles Sega and Orange, the mobile telephone system.

PR was a vital part of the Sega campaign, Cowie explains. Sega's 'event advertising' has included the release of a pop single, by Right Said Fred, to promote the launch of Sonic 3. The group sang live outside Sega's headquarters and featured heavily in youth magazine interviews.

Ending up with just another ad is every advertiser's and agency creative's worst fear. So the quest to push the boundaries further seem unstoppable. Only last week Mazda launched a commercial comprehensible only if the ad is video recorded and replayed slowly.

But other advertisers should bear in mind what Tango found out the hard way - that the tolerance of the public can only be stretched so far.