hi i have rang up ntl virgin media that i no longer require there services as i have had a better offer from talk talk

the problem is there have told me that an engineer will come and collect the box on december 3rd prior to that he will phone me. the problem is i threw away the original box i only have the chipped box which i purchased few years ago from a seller on a forum. which the boxes do not work since there went nagra 3
i cannot give them the chipped box. what do i tell the engineer when he comes for the box on december 3rd

please help

thank you