It was working earlier (not got my PAC yet so couldn't use it) but it's not now. Also the Support page no longer displays the link whereas it was there earlier.
EDIT: Logged out, cleared browser cache, closed browser, launched browser and went to giffgaff.com > Support. Second row menu showed only "FAQs | Ask the community". Logged in, then seond row menu had all items: "FAQs | Ask the community | Messages from agents | Transfer your number | Lost & Stolen". Transfer your number page working again.