New rules coming into force next week will allow the Advertising Standards Authority to investigate and halt such scams. The new codes will also include a clearer definition of what constitutes fair comparative advertising in the wake of bitter price wars involving supermarkets, telecoms companies and airlines.
The rule-making Committee of Advertising Practice has updated its codes for the first time in almost three years to take into account new Government laws and European directives on data protection.
The codes also recognise the growing importance of direct marketing by overhauling the rules governing it, and giving it equal status with above-the-line advertising.
Guy Parker, the CAP secretary, said: "We have increasingly found that a lot of people working in direct marketing don't realise that the code also applies to them."
The amended codes also beef up the rules on alcohol advertising, which must not suggest that drinking can overcome boredom, loneliness or other problems, or that alcohol has therapeutic qualities.
At the same time, regulations governing car ads are being strengthened with tighter restrictions on encouraging anti-social or irresponsible driving.
The new rules no longer cover tobacco advertising, which is now banned, although CAP executives are in talks with cigarette companies about the promotion of rolling papers, which is still permitted, and point-of-sale material.
Andrew Brown, the CAP chairman, said: "Effective self-regulation is tantamount to ensuring that consumer confidence in marketing is maintained. For this to continue, we have to ensure that marketers have clear guidelines on how to keep their communications legal, decent, honest and truthful."