Cheers for the help guys. Doesn't really look like its going to be something my side that I'll be able to sort so its just a case of leaving it be and hoping they don't get worse over time.
I guess I could try a different modem, or modem/router combo like a Billion or something, no idea if they'd handle errors any differently. I know I didn't really have any issues with the Home Hub 5a (apart from its lack of features and poor wifi), but not being able to see full line stats bugged me a little, for all I know I could have been seeing the same error count on the HH without realising it.