You almost have to laugh. As every part of the UK goes down the pan due to greed and incompetence, even the tax office join in the fun. The darkly humorous thing is that these companies make such a bodge of things, but still think they are clever enough to get themselves out of it, only to again bodge the whole thing through basic incompetence with such trivial things as sending out a letter.
Shocking state of affairs down at HMRC. We're not just 'in it together', but it's actually all our fault.

[url]http://www.thisismoney.co.uk/money/news/article-2050648/HMRC-hides-errors-stop-taxpayers-appealing-unfair-demands.html[/url]

This excrement has been happening for years. It became much worse when the last government merged the Inland Revenue with Customs and Excise to 'save money'. They created a new computer system to link the two seperate systems at great expense, only it doesn't work. HMRC is great at not recognising its' own mistakes (just like that other bloated government body, the DWP) and it is not surprising a culture of covering it up has not only begun but has become seemingly endemic.