4G mobile operator EE (formerly Everything Everywhere) is being investigated by Trading Standards following a complaint that its advertisements are "grossly misleading".
According to a report in The Telegraph, a man from Plymouth has complained to Trading Standards over a poster in his local EE store which claimed that "4G is here," even though the nearest 4G signal to Plymouth is 120 miles away in Bristol.
The poster claimed that the iPhone 5 was available on the superfast 4G network in Plymouth and was five times faster than phones on 3G.
"That is a lie," said Jon McKnight, who filed the complaint. "I believe it is misleading in the extreme to suggest that an iPhone 5 bought in Plymouth would work on 4G when that service is not available here and no date has yet been announced for its introduction."
EE said that the poster in the Plymouth shop was put up in error and had since been removed.
"We have over 700 EE stores across the country and would like to stress this was an isolated error for which we apologise," a spokesperson said.
However, Trading Standards officers in Plymouth have warned that there is likely to be a nationwide problem with adverts, as EE is continuing to running its campaign in areas where 4G services are not available.
EE responded that it is important for the company to raise awareness of the new brand and network through a national campaign across the UK, even in those areas that do not yet have 4G coverage.
"However, we won't be advertising 4G overtly in those stores that are not in 4G covered cities," said EE in a statement.
EE's 4G service currently available in Bristol, Birmingham, Cardiff, Edinburgh, Glasgow, Leeds, Liverpool, London, Manchester, Sheffield and Southampton. The service will be available in a further five cities before Christmas, with more cities and rural locations planned for 2013.
EE intends its 4G service to be available to 98% of the population by the end of 2014.