NI Story - March Episode

So back in January I started trying to pay a National Insurance contribution bill that HMRC had sent through, as I was short for a tax year.  

In February the amount bounced back to me, as the account details they've given me were out of date, and the account had been closed.  I ended up sending a cheque and thought that was the end of the matter.

Well it's now March and the story came back to life!  I received 3 little brown envelopes on Saturday and by fluke I opened them in this order:

• Thank you for paying your missing NI contribution, you now have a complete tax year (08/09) for pension consideration
• It has come to our attention that you have overpaid your NI contributions for tax year (07/08), due to an error on your employers part.  You are now due a refund, and you will receive a cheque within the next four weeks.
• The cheque!

I've almost got all the money back that I paid them for the following tax year...and how come they've found the error now?!?!?  A most random experience....is God having a bit of a laugh...and is it the end of it....