Happened to me
About 8 weeks ago the letter arrived alleging an overpayment on £307 op allowance in December 2006. I left the light blue September 2007 - what joy. There was no supporting documentation which irritated me a little so wrote back requesting they prove their case. In the meantime I checked pay and bank statements etc and yes there had been the same payment on consecutive months - bang to rights. The evidence when it arrived was two pages of a JPA screenshot showing £307 on the December and January - you know the thing; a grey box on a lighter grey background with 307 placed in the centre. Meaningless to the lay person but bang to rights from my own research. Of course bottled the intention to payback a pound a month and went for £50. Anymore surprises I wonder?