I've provided a link to the relevant official site in your other thread.
You can only file a notice of disassociation in respect of a real person. You can't do so in respect of someone who appears to be you.
For example, John and Mary might live together and share their finances. Unsurprisingly, if Mary applies for credit, John's credit status will be taken into consideration. But let's assume that they split up, live at separate addresses and have no further financial connection whatsoever with each other. Mary would then be extremely annoyed if she found that she was being refused credit because John had massive debts. So she could file a notice of disassociation.
Now, as a second example, consider Sue Smith. She finds that she's being refused credit because a total stranger has fraudulently been applying for credit in her name after 'stealing her identity'. Sue will obviously want to make the police and credit card agencies (together with anyone else who might think that she owes them money) aware of the situation, but she can't file a notice of disassociation since she'd have to disassociate herself from 'Sue Smith', which is herself!
If you want to file a notice of disassociation you can do it online:
http://www.uk.experia...nedisassociation.html
(That link goes to the Experian website but they pass on the information to the other two UK credit referencing agencies, Call Credit and Equifax)
Chris