Make sure that you have inadvertently introduced a space at the end of the PPP username and password as this can happen when copying and pasting as this will be passed to their radious server and might prevent successful authentication (first I've heard of this company so if they don't use one, apologies)
Might be best to paste what you've copied into Notepad (or the mac equivalent) first as this will show up
Virgin (ADSL) => Namesco => Newnet => O2 => Plusnet => Zen => Newnet => Zen => Freeola => Vivaciti (using O2 Wholesale DSL) => Xilo (C&W Wholesale) => Xilo (O2 Wholesale) => Xilo (TT Wholesale due to O2 Wholesale closure) => Zen LLU =>> ZeN FTTP (Openreach 300 Mbps down, 47 Mbps up)
Router: Fritzbox 7530
Note: I don't lay turf for anyone. astro or otherwise, all views and opinions expressed are my own based on experience.