A national press ad, created by Grey London, and a page on the Vodafone website were both ruled against by the advertising standards watchdog today.
The ASA warned Vodafone not to imply it performed better than other mobile phone operators on call connection and dropped calls performance across the UK unless they have "suitable substantiation".
The text in the press ad stated: "Every ‘We've found your dog’ ‘We've found your wallet ‘We've found you a donor’ matters ... Many people on the UK's transplant waiting list never go anywhere without their mobile; in case they get that call that could change their life. We're unbeatable at connecting your calls. Because to us, whether life changing or not, every call matters".
The Vodafone website page featured a banner with text that stated "Our network Unbeatable at connecting calls ...".
Both ads stated in small print at the bottom that the information was based on call connection performances across 26 towns and cities versus three main competitors during April 2014 by Vodafone.
However, a complaint was issued by Hutchison 3G UK, which owns the rival Three brand, which challenged whether the Vodafone claims were misleading and could be substantiated.
Vodafone said it felt the claims were acceptable because no other mobile network operator could beat them on performance for call connection or keeping calls connected.
The data had been collected in November 2013 and April 2014 by an independent third party across 26 towns and cities in the UK, which then compared Vodafone’s performance against the three competitors.
The ASA recognised that Vodafone had taken a "robust approach" to its testing of the data. But it raised concern that the cities, towns and routes used to collect the sample appeared to be limited and noted that it excluded large areas of the UK.
The advertising regulator said it had concerns as there were no locations in Wales or Northern Ireland and that the two Scottish locations were approximately ten miles away from each other.
It ruled: "Given that large geographical areas of the UK were omitted from the sample, we considered it was insufficiently widespread to be considered a true representation of UK consumers’ experience of call connection and dropped calls.
"The ads must not appear again in their current form. We told Vodafone Ltd not to imply they performed as well as other mobile network operators on call connection and dropped calls performance across the UK coverage unless they held suitable substantiation."