I haven't had a Cardcash account with them for many many years.
I asked her when the last transaction was. It was quite recent -- interest debited from the account, by the Halifax themselves.
I asked her when the last real transaction was.
She went back as far as her computer can go. She can't find a real transaction, one that isn't interest.
I've suggested that she finds out when the last real transaction is, and when she discovers that it was during the mid-1980s, that she writes off the balance and closes the account.
Of course she has no power to make that decision. She's going to do some finding out, and phone me back if she needs to.