Upload speed halved in past few days

For some reason my upload speed has more than halved in the past few days. As someone who uses the cloud a lot and uploading to you tube, this has a huge impact. I've been getting 20mbps pretty constantly since I joined and since Monday I've only been getting 9mbps. Download speed is fine at a stable 73mbps.

I've rebooted the hub, swapped the microfilter and disconnected every other device on the line and nothing seems to help. I even did a speed test at 2am and it was the same so it isn't like a massive amount of people using it at the same time.

Is there anything else I can do?