VAT, HMRC, and their employees Moe, Curly and Larry.

Letter from the VAT man to me, late September (paraphrased from memory):

We have determined that you owe us £1,057.00 -- please pay up pronto, melonfarmer, or we'll haul your sorry ass into court.

Early October: *me pays*

Letter from the VAT man to me, mid December (quoted accurately but abridged):

A routine audit of your VAT account has revealed that there is a credit of £1,057.00 for which, at present, there is no corresponding liabilty.
Detals of the credit are as follows:
ELECTRONIC PAYMENT 12/10/11 £1,057.00
Please check your records and indicate, by ticking the appropriate box which of the following applies to the payment.
1. I have submitted the remittance in error. Please return the payment. [ ]

There being no boxes to indicate "I submitted the remittance when you demanded the money with menaces you complete twonks", I will tick box one and return the letter.