Lower than expected sync speed with higher SNRM and G.INP

[#1]

Hi,
I'm connected with a fully updated HG612 and my line recently had G.INP enabled upon it. I currently sync at 66999/20000 with a downstream SNRM around 8dB.
I think my line is banded, and is capping me at the 66999 figure, as my target SNRM ought to be 6dB? Is the banding something that Plusnet have control over, or is it just a case of waiting to see if/when DLM relents and gives me a higher sync at 6dB SNRM?
Andy.

[#2]

the latter I am afraid

[#3]

Thanks Jim.
I had a shaky DSL-AC68U on my line for some months before I switched back to the HG612, so I think DLM is being particularly cautious moving me back up - The AC68U was continuously erring and I got banded quite severely at the time.
Andy.