Carphone Warehouse's drive to shake up the broadband internet market could face a serious roadblock in the form of a censure from advertising watchdogs.
The mobile phone group unveiled "free" internet access last week in a blizzard of marketing and public relations activity, but adverts bragging that customers who sign up to a £9.99-a-month TalkTalk home-phone deal get "free broadband forever" have attracted scores of complaints.
The Advertising Standards Authority said yesterday it has opened a formal investigation into the ads. It could possibly force Carphone to ditch the entire campaign.
If the ASA rules against the company, it would throw the Carphone chief executive Charles Dunstone's business plan into disarray.
Mr Dunstone claims Carphone will lead a revolution in the internet industry, sending prices down and leaving competitors such as BT in its wake.
The ASA has had more than 40 complaints so far, with more arriving every day. Most are from the public, though BT is one of the corporate complainers.
A spokesman for the watchdog said: "We are looking into these complaints. We can't yet say if we will uphold them."
There are three main objections to the ads. One is that the service is not as widely available as claimed. A second is the use of the term "forever" and the third is the claim that the service is free, given that customers must sign up to TalkTalk and pay a £30 connection fee.
Carphone dismissed the idea that the ads were not truthful. A spokesman said: "Every major campaign gets some complaints."
The telecoms group has not yet been contacted by the ASA.