credit card default on credit file

wardo_2

I have just been declined a increase of my overdraft due to bad credit rating, I was unsure to why this would be, so checked my credit file.
I discovered on file I had a debt of £1800 to Cabot finance. After checking the dates the card was taken out I assume it is from a credit card I had back at the start of 2003 with a limit of £250. I moved house a few months later providing a forwarding address which the company failed to use. I forgot all about the card (stupid I know) for the past 6 years. I have made no payments on this card since at least June 2003 which would now, I believe remove this default? Looking at my credit file it states I defaulted July 2004 with a balance of £1200, this is completely un-true as I had moved house the previous year with no contact from the company. The information for this default was updated on my file may of this year.
I'm not quite sure how to remove this default but am looking to take on a mortgage in the next year and apart from this one problem my credit file is all clear, showing all payments on time.
I appreciate any suggestions

balmk

First port of call would be to conatct the finance company involved. If you moved adress and they had not updated their records, they may have sent replacement cards to your old address which could have been used fraudulently.