Many British businesses are losing money and alienating their patrons because of poor customer service, a consumer group has warned.

Across Britain, companies are relentlessly pitching to their customers, treating them in a dispassionate manner that often suggests more concern on making a quick sale than forging a long-term client relationship, claims the National Consumer Council (NCC).

This trend of "over-promising and under-delivering" it says is lending to a view amongst consumers that businesses are incapable of getting the most basic things right.

"NCC wants British business to succeed, but our research over the past year and a half reveals an extraordinary picture of companies self-harming," said Philip Cullum, deputy chief executive of the NCC.

"We're seeing more and more 'service rage', with infuriated customers punishing companies for hopeless performance. The scale of company ineptitude must amount to many billions of pounds of lost profits."

Cullum said that people believe that businesses have no idea what it feels like to be a consumer.

In particular, consumers cite electrical retailers, garages, telecom and financial services as among the worst offenders.