Well... do you have a choice to say no? If you'd like to stick with them, get the new ONT (make sure you don't pay cause... why should you? It's not your fault). Otherwise switch over to another company in your area.
Speaking of which, what FTTH alternatives do you have in your area, and in Karachi in general? I know there's PTCL and SF... and Transworld... and that's it?