Carphone Warehouse is to double the pace at which it converts UK outlets to its wireless store format.

The retailer will roll out the format, which includes dedicated broadband advisers and wireless products for immediate purchase, to 200 stores over the summer. It has converted 100 in the past financial year.

The retailer wants to drive growth through products and services outside its core mobile phone business.

In its fourth quarter trading update this week, Carphone said its store openings programme will be “more measured” because of the “softer economic climate”. It will open 120 stores and re-site and refit 200, as well as focusing on larger formats.

In the US, it will accelerate the roll-out of its Best Buy Mobile format in Best Buy stores with the aim of completing the project in the autumn – a year ahead of schedule.

Carphone’s share price fell 13 per cent on Tuesday after jittery investors focused on missed revenue forecasts and slower broadband sign-ups in its update.

Finance director Roger Taylor said he was “totally mystified” by the stock market reaction. “In the current market, people want bad news,” he said.

Carphone said pre-tax profits will be£215 million to£220 million for the year to March 31, slightly below market consensus of£225 million. While mobile phone sales were up 12 per cent to 2.7 million by volume in the fourth quarter, broadband sales were 109,000 below forecasts.

Separately, Carphone Warehouse chief executive Charles Dunstone told Retail Week there “had been an extraordinary reaction” from customers after the retailer this week slashed the price of the iPhone by£100 to£169 as part of a limited offer.