I'm trying to help a customer out with some connectivity issues they are having with their VDSL line, they have sent me a photo of the router
DSL LED and it is steady amber,am I correct in thinking that this indicates that is synced but using ADSL not VDSL.

The manual does not mention that the DSL LED can be amber but when their connection is working this LED is green.

It's a sync issue, but more *likely* an issue with username/password, i.e. sync with the DSLAM equipment has been established, but credentials incorrect.