The bank have to prove that you agreed to be party to the account, and that will be confirmed when they send you copies of all documents that they claimed you have signed. You will need to read them carefully to establish whether you have any liability.
In truth, Debt Free Direct are not acting for you, so they really do not owe you any duty of care, but professional courtesy to their own client would indicate that they could be helpful in trying to resolve this for you both.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
To have me propose an IVA for you, please visit:
http://www.melaniegiles.com/ivaEnquiry.asp
See customer feedback at:
http://www.iva.com/iva_companies/IVA_Advice_Bureau.asp