Could be something as innocuous as accidentally making a booking for one client whilst logged into another client’s account. Could be something more nefarious.

Either way BA know what she’s done, she likely knows what she’s done too, and she’s trying to fob you off and ‘make this go away’ by transferring the blame.

If she was innocent why would she not be trying harder to protect her reputation by fighting BA for wiping out $100,000 worth of her clients’ Avios?