Yes, I use the www.SayNoTo0870.com site a lot, but you can't always get alternatives.
A recent example is the JobCentre, I made a call that lasted 62 minutes and cost me £6.45. I didn't get to speak to anyone or get the chance to request a call back for the first 54 minutes of that.
Following this I complained via my MP and got a rather bland response from Iain Duncan Smith about government departments and how 0845 is the best option.
Thanks for the link to the Which campaign, duly signed
Interesting to see in a related page - http://www.which.co.uk/news/2013/09/government-to-re... - that the DWP are now considering 0345, which would be inclusive in my mobile minutes. I only have a basic 'weekend' package on the landline.

You may also want to use this: http://www.weq4u.co.uk/

I have no idea how they can offer the service, but it works ...

Great idea - use VoIP on an MVNO hosted on a network that has the worst 3G coverage in the UK.

Have added it to my mobile - thanks, good find !