I assume you mean NOW broadband, as refunds are not generally made for TV services? That being the case the money should be returned to your account to the same payment method you used. I think you may have to wait a few weeks for that to come through. If you need to chase it, contact the support team on 0330 041 2518.
If this is for broadband, the refund is normally credited back to your payment method when your next payment would have been due. Unless, of course, you cancelled your direct debit at the same time as you cancelled broadband. In which case contact the broadband team.
If, however, you are talking about cinema/entertainment etc., then there is no automatic refund, so you’ll need to chat to customer services using the “how to contact us” at the bottom of the page.