You probably need a new NTL:250 modem, but you would only get one if your existing
heap of junk proved to be faulty. Ntl will replace it for you but it'll cost you £50!
One way of avoiding the charge is tell them you want to quit (assuming your not still in your 12month contract period) and ask to be put through to
retentions which is the department that tries to keep you as a customer. It's possible to get them to drop the £50 charge.
Nothing wrong with that router.
Good luck!