Ewan MacLeod was angry. He had been charged for sending an e-mail from a mobile phone via a package that claimed to offer free, unlimited data usage.

Months after he had written about the experience on his blog, Mr MacLeod was surprised to receive a call from the mobile phone company, 3, inviting him to meet chief finance officer Frank Sixt. Apparently, someone had posted his comments on the company’s blog, set up to promote the free service.