non-existent products as a means of assessing likely public demand, should such a product be offered in the future. c) Where it becomes clear that an advertised product is not available, (in circumstances where the public are not likely to assume from advertising its ready availability) immediate action must be taken to ensure that further advertisements for the products are promptly amended or withdrawn. (xiii) Guarantees a) The word 'guarantee' should not be used in any way that could diminish consumers' legal rights. Substantial limitations should be spelt out in the advertisement. Before commitment, consumers should be able to obtain the full terms of the guarantee from advertisers. b) Advertisers should inform consumers about the nature and extent of any additional rights provided by the guarantee, over and above those stipulated by law, and should make clear how to obtain redress. (xiv) Comparisons a) Advertisements containing comparisons with other advertisers, or other products are permissible in the interest of vigorous competition and public information, provided they comply with the terms of this section. b) All comparative advertisements shall respect the principles of fair competition and shall be so designed that there is no likelihood of the consumer being misled as a result of the comparison, either about the product advertised or that with which it is compared. c) The subject matter of a comparison shall not be chosen in such a way as to confer an artificial advantage upon the advertiser or so as to suggest that a better bargain is offered than is truly the case. 25