Speedy you haven't said whether you still live at home with your mum. What the issue could be is if she has been receiving full housing benefit and you have been living there and part of the time you have been working she should have notified them of this change in circumstances. As an adult non dependant living in the home would mean a deduction in her housing benefit....
sorry if this isn't what you want to hear but it may help you be prepared for when you go to the offices... any questions, just ask
