Hi @PeterY1 sorry about the delay getting back to you, I'm chasing an update with our suppliers and I should know more by tomorrow.
My tests show the errors are quite bad on the upstream so I am making an adjustment on that to try and help the connection stability.
BT Smarthub arrived. Unfortunately no difference in upload speed.
Openreach came on Friday 8 March and strung a dedicated 200-250m line from my house socket to the point where it goes underground. It may have slightly improved download speeds but I have not dedected any improvement with the primary upload speed issue.
What has not been tried yet is a port swap at the cabinet incase something is faulty there. I also wonder if I am being capped on the upload. When I do a speedtest the needle always flicks up to 5Mb/s before dropping. I once got provisioned on a capped service before and saw the same thing during speedtests (albeit on the download).
Over to you for though for next steps!