Juniper SSG320 problems with a 21CN ADSL2+ Line

Hi,

I have a SSG320 with a ADSL2+ PIM card and it worked fine on ADSL (upto 8mbit) fine for years.
Now we have switched to ADSL2+ on the 21CN network the line keeps dropping out at random times and it can take 15 mins to re-authenticate the link.

This is from the logging on the unit.

2011-04-13 12:11:56 system notif 00558 PPPoA ADSL connected successfully.
2011-04-13 12:11:56 system notif 00572 PPP authentication state on interface PPPOA: local authenticated itself successfully.
2011-04-13 12:11:55 system notif 00572 PPP LCP on interface PPPOA is UP.
2011-04-13 12:11:55 system notif 00572 PPP LCP on interface PPPOA is DOWN.
2011-04-13 12:11:54 system notif 00572 PPP LCP on interface PPPOA is UP.
2011-04-13 12:11:52 system notif 00558 PPPoA ADSL started negotiation.
2011-04-13 12:11:52 system notif 00558 PPPoA ADSL connection attempt failed (LCP, CHAP/PAP, IPCP link setup).
2011-04-13 12:11:49 system notif 00558 PPPoA ADSL started negotiation.
2011-04-13 12:11:49 system notif 00558 PPPoA ADSL connection attempt failed (LCP, CHAP/PAP, IPCP link setup).
2011-04-13 12:11:48 system notif 00572 PPP LCP on interface PPPOA is DOWN.
2011-04-13 12:11:48 system notif 00572 PPP authentication state on interface PPPOA: local failed to authenticate itself.
2011-04-13 12:11:48 system notif 00572 PPP LCP on interface PPPOA is UP.
2011-04-13 12:11:48 system notif 00572 PPP LCP on interface PPPOA is DOWN.
2011-04-13 12:11:47 system notif 00572 PPP LCP on interface PPPOA is UP.
2011-04-13 12:11:45 system notif 00558 PPPoA ADSL started negotiation.

Any ideas would be great!!

So far we have replaced the filters, all cables, changed the firmware on the unit.
our ISP Zen can see the line dropping but all they can offer is to get BT out, but might be chargeable etc....

And the ADSL stats are?

Between around 42dB and 53db attenuation ADSL2+ can be marginal and forcing kit to use ADSL2 or ADSL modes can be more stable.