some years ago, i was signing on, and WORKING WITH MY NATIONAL INSURANCE NUMBER at the same time (iwas on a night shift )......... this i did for about three months, -then i stopped the night shift job....some months later, I had to speak with an official from JOB CENTRE PLUS - and they said "some one was using your N I number btwn - Sept = Dec 2004 .....working at ???? company I said to the official no "that was me " ....(on the night shift and recieving - J S A ) ....... I worked it out that I recievd in Job seekers allowance �600- six hundred quid- anyway the official told me ok....we will be writing to you in due course....... they did , i was expecting a letter saying that they would want the �600 - back in monthly installments,,,,,,,when i did read the letter the came to an amount of �150 --- is what I should pay them back ! ....that was fine with me,,,,,so i made arrangements to reimburse them for �150 ...they call it an "overpayment ".....so i had to pay them a quarter of what i was not really entitled to recieve,,,i was sort of quids in ,,,,,really ---- this was JOB CENTRE PLUS , (not housing/council tax benefit - i will point out )......