Has there ever been any default on the loan or reason they could have got the court to grant a charging order which is registered on your property?
You can check whether it's registered on the title (in the proprietorship register) or there is a notice or restriction on for a charging order by downloading a copy of your title from the Land Registry here for �3.00...
http://www.landregisteronline.gov.uk/
If you're not sure, ring your local Land Registry and they shold be able to explain what has been put on in what circumstances....
http://www1.landregistry.gov.uk/contact/contac ts/
Have you got anything in writing about it being an unsecured loan?
This is the site of the financial ombudsman...
http://www.financial-ombudsman.org.uk/
They may be able to advise further and maybe help you sort things out.
Also the FSA as they are likely to be FSA registered...
http://www.fsa.gov.uk/
There are some firms who can take on cases for misselling.