With that sort of thing unless you'd signed as a guarantor, they'd have great difficulty getting any money. All they can do is write you stiff letters. I don't know if you found this, but after a while the letters assume a wheedling, almost pathetic tone. 'Mrs. Smith, please work with us to resolve this . . .' If you respond, it encourages them as it shows it's a 'live' contact.
Yup, the shredder did stirling work ...