I would also like to know on here who has disputed and won. Looking at all the paperwork they sent through the post they f*cked up majorly and ended up writing that my OH works 48 hours a week but earns a big fat £0, so we've been getting almost the full amount of tax credits when we shouldn't have been. Even though we rang them up and told them his hourly rate and how many hours he works! I'm going to have to sell all my possessions to pay this amount back!
This happened to us as well, i rang them and gave them all the details over the phone and the dozy mare put 37.5 hours a week=£000 stupid bint. So now we owe them a fair chunk of money. I put in a complaint which they 'investigated' and sided with the dozy mare, i dont get how i can be penalised for giving the full correct details yet some stupid bint who cant even put numbers into a box gets away without a warning and im left to pay them back for their cock up.