It gets better. In order to be seen to 'not be profiting from the use of an 0845 number', DWP didn't collect the 0.5p per minute revenue share payments they were entitled to. Instead, they just let their provider keep the money. Later they used it to barter a discount for other services.
Margaret Hodge and the Public Accounts Committee got to the bottom of things in September 2013.
See
http://www.bbc.co.uk/democracylive/house-of-commons-23934512 from the beginning.
This led to the Cabinet Office publishing their Guidance in December 2013 and DWP changing to 0345 numbers in March or April 2014.
Additionally, in December 2013, the Student Loans Company was savaged by Margaret Hodge and the Public Accounts Committee over their failure to move away from 084 numbers after it was highlighted at a previous enquiry some 5 months earlier.
See
http://www.bbc.co.uk/democracylive/house-of-commons-25339852 starting at about at 1h36m
Those actions, among many others, got us where we are today. Very few public services retain usage of 084 or 087 numbers.