A reason why the official inflation rate may not represent the cost of living

Toblerone! Thanks to Sky
http://news.sky.com/story/toblerone-fans-distressed-as-bar-changes-shape-and-gets-smaller-10649876
and the BBC
http://www.bbc.co.uk/news/business-37908692
and
http://www.bbc.co.uk/news/uk-37904703

Apparently, it's called "shrinkflation". Thanks to economicshelp for this summary
http://www.economicshelp.org/blog/24369/inflation/shrinkflation/