According to the Consumers' Association, 70% of people who move from BT to another phone service provider end up with smaller bills.

In a Which? survey of 19 telephone providers, only NTL was rated worse than BT.

Which?'s Neil Fowler said:

"With smaller companies and supermarkets overtaking traditional providers, they're in danger of being knocked off their perch if they don't start treating their customers better."