IPv6 not working with IPv6 ISP

I have a Peplink Balance 30 with firmware version 5.4.4 build 1500.
My ISP in Australia (Internode) is the only ISP that supports a dual-stack IPv4/IPv6 PPP session.
Unfortunately I am unable to get IPv6 working.
The ADSL modem is configured for bridged mode and the WAN connection on the Peplink Balance 30 is configured for PPPoE.
I have enabled IPv6 in the ‘Network’ section of the Peplink admin interface, as well as selecting the correct WAN connection.
I have also enabled IPv6 at the ISP end through their web interface for my broadband account.
I then telephoned Internode to try and debug this issue and they could see from their end that the Peplink was requesting an IPv4 address but nothing IPv6.
Internode’s FAQ on IPv6 is here: Internode :: Support :: Guides :: Internet Access :: IPv6 :: FAQ
In particular it states:

How do hosts on my LAN obtain globally routed IPv6 addresses?

Your IPv6 Access Device/router should assign /64 subnets to its interfaces after it obtains a DHCPv6 PD lease. It should then offer the prefix to your hosts via IPv6 Stateless Address Autoconfiguration. In more complicated set-ups, you may choose to use DHCPv6 as well.

They also have the setup for Linux/BSD here: Internode :: Support :: Guides :: Internet Access :: IPv6 :: Linux/BSD

Please help.