I wouldn't waste time on Barclaycard in terms of discussions with them.
You need to write back saying you believe that the Information Commissioners Office has ruled that most filing systems will fall within the scope of the Act and that you want your statements.
I have heard nothing from our contacts at the Information Commissioners Office to suggest they feel differently about Barclaycards system from abbeys or indeed anyone Else's filing systems.
If you don t get your data within the 40 days complain to the Information Commissioners Office, if your feeling awkward then send them the
LBA for non compliance giving them 7 days for compliance as well.
when they fail to provide the data after 7 days then you can also issue a claim in the small claims court.
HTH
Glenn