So all the people on motoring are thick are they?
http://www.theanswerbank.co.uk/Body-and-Soul/Q uestion301893.html
Insurance Companies do not like people who try to fraud them which your friend is obviously trying to do, they are not stupid. They will not pay for repairs when at the time of the accident they were not her insurers.
Your friend should own up now and tell them exactly what happened, perhaps they will stop the investigation. Tell them it was a mistake unless she deliberately tried to defraud them.
She could get in touch with her previous insurers and see if they will pay for the repairs but due to the delay I doubt it.