Having just read a post just now from Jojocox, about dear phone calls, this has jettisoned me into making this post.
saynoto0870.com is a really good site to seek the cheaper alternative number for most companies.
I've tried Freeman Jones and there is a Freephone number. I haven't tried all, but most banking institutions have freephone numbers....but don't advertise it.
It's a good site, totally free and could save you lots.
I hope you find it useful. To celebrate my usefulness, I shall crack open a can this evening.
Completed IVA - August 2012 pheeeeeeeeeew
Only my opinion - Nothing More Nothing Less
I use that site. I would also recommend the WeQ4U app if you have an iPhone (not sure if it's available on Android) - you phone the 0800, 0845, 0871 etc number and it most cases it will find an alternative number that comes out of your free minutes.