Superfast Fibre slow even when connected via ethernet

[#1]

I've been on Plusnet's super fast fibre package for a couple of years now and we've never had fast broadband. I'm coming to the end of my tether as I sit here with my laptop plugged into router via ethernet and it's still slow. I've done all the tests at various points - has anyone else had this, what was the problem and how did you get it fixed? Plusnet take forever for support on anything....

[#2]

Good Morning, 

What speeds do you get when testing on speedtest.net and speedtest.btwholesale.com ? I'm checking a few things from our side now

EDIT: I've tested your line and it is syncing at 79.9Mb/s download and 20Mb/s upload, no issues found with automated testing, this doesn't rule out an issues entirely but it usually a good indicator of something else being at play