Red faces all round at the Carphone Warehouse today, when it announced a £12 per month unlimited data plan that included a handset, 200 call minutes and – most surprisingly – no fair-usage policy.

The company’s UK trading director Mark Eastham underlined the surprise element of the all-you-can-eat package with a press statement, stating: “There’s no small print or fair-usage policy, so when we say ‘unlimited internet’ access we really mean it.”

The only problem was that a quick trip to the site to check the availability and, perhaps, even, place an order revealed the dreaded asterisk right next to the “Unlimited MB” column in the feature list. The asterisk led to the familiar footnote: “subject to fair-use policy.”

Some mistake, surely? According to Carphone Warehouse, the confusion arose because the software used to put its site together couldn’t be altered to remove the asterisk from the template without changing pages for every phone and deal on the site. Unlimited data? Computer says “no”.

The company says the site will be updated overnight, and although the asterisk will remain in place there will be a footnote to the footnote highlighting that the fair-use policy doesn’t apply to this particular Talkmobile package. Utterly confusing.

Carphone Warehouse should obviously have got that caveat in before launching the product, but it shouldn’t detract from what genuinely looks an attractive offer.

Apart from making the company look foolish, the mixed message highlights the usual attitude of the mobile carriers to unlimited data – it’s such an alien concept that even when a company wants to give it away, it trips over the industry’s default terms and conditions.

Earlier this year, Canon blamed none other than hapless ex-England manager Steve McClaren for costing it millions of pounds of digital camera sales. Why? Because Canon was one of the official sponsors of Euro 2008 and thanks to the umbrella man’s incompetence, fewer footy fans would stop mid-game, turn to their mate and say: “Sod this penatly shootout, I’m popping down to Dixons and picking up an Ixus” every time the Canon logo appeared on screen.

Now the Carphone Warehouse’s Charles Dunstone is blaming his company’s sliding broadband sales on the property slump. “One of the key times people change broadband provider is when they move house,” he claims in today’s Times. “If you’re not moving house, the catalyst to make you think about changing provider does not exist.”

Hmmm… I’d say the main catalyst for switching broadband provider is shocking service from an ISP. And how did Carphone’s TalkTalk rank for customer service in the most recent PC Pro Awards? A mighty two stars out of six for customer support and one for reliability.

Perhaps Mr Dunstone should be looking a little bit closer to home?