Hi, this is Jim, thank you for the question - I will do my best to resolve this quickly for you.
Sorry to hear of the issue. You need to make a complaint to the lender which issued the default and who registered the fraud marker against you - if they uphold your complaint they can remove the marker. The lender will have a complaints policy. I note you say you need a mortgage as soon as possible but the only way to get a marker removed is either the lender removes it voluntarily or the Ombudsman forces them to.
You have to make a complaint and exhaust that with the lender before you can involve the Ombudsman. In terms of a fraud marker this can be dealt with at the same time as the default notice.
If the lender rejects your complaint then ask them for a final response letter (a "deadlock" letter) and then you need to escalate the dispute to CIFAS themselves who will do an independent review of the case. The address to write to is :
6th Floor, Lynton House
7-12 Tavistock Square
That should take no longer than 14 days to complete. If CIFAs agree with the company which registered the marker, you would have to escalate it to the Financial Omudsman Service (http://www.financial-ombudsman.org.uk) who can review the evidence and they can order the CIFAS marker to be removed.
If you want to find out if CIFAS holds any fraud data against your name, you can make a subject access request to them here:
I hope this helps and answers the question which is easy to understand - please feel free to ask me anything else. I will reply as soon as I can to help with any further queries.
Thanks for using our services and have a good day,