What are the line stats on it like SNR and loop attenuation? Maybe the ISP has raised the SNR because of the disconnections?

Just found out Bt are in the process of installing fibre to the cabinet at the end of the road ( a couple of hundred yards away! So with a bit of luck I may be able to get around 24mb That will be a nice change from 1ish.

Seen the men digging and installing strange new ducting next to the box. Fingers crossed. Now where's that list of unmetered isps ;-)

Voodle heres the output from the router:

ADSL Status Mode State UpSpeed Down Speed SNR Margin Loop Att.
G.DMT SHOWTIME 448000 1280000 7 66

That Loop Att at 66 is bad but we are far from the exchange. I have previously seen it from 63 to 67

Its not looking good....

Lucky that they're putting in fibre to your cabinet, the SNR shows that it's as good as it's going to get with that modem code 6 is generally the lowest you'd want to see for a stable line.
Maybe you could try different ADSL modulation types on the PPPoE/PPPoA settings page? It might be that the billion router is connecting using ADSL2 and getting the higher speeds that way.

Thanks for the assistance Voodle. I'll try changing the settings in PPPOA. I just spoke to my ISP (Zen) they say to get the speed from the fibre connection to the exchange you need VDSL hardware

So that sounds like a VDSL router - wonder if Draytek will offer VDSL as a firmware upgrade ;-)