Thanks for the response guys, apologies for not getting back in touch until now.
So, whatever the issues, given repeated queries to Vodafone all they respond with is:
As mentioned above, the Sure Signal is designed for PPPoA.
The bridge setting on the router should work to allow PPPoA devices to run, but you'd need to check this with your ISP directly.
Can anyone clarify what exactly they mean by bridge setting and if my router (Tplink WD9980) can actually do this? It does appear to have bridge functionality, I just don't know if it this is what is required and what if any settings it needs to get around the PPOE/ PPOA.
Many thanks,
Mike