Spoke to CS earlier, but have decided against it for now. It's £17/month more for me than it is for a new customer on a like-for-like bundle. The guy seemed insistent on giving me the benefits of phone upgrades for a couple more quid a month, even though I told him several times that I don't have a phone plugged in and only have it because it somehow makes my bill cheaper.
I'm probably grumpy, since I had a price hike and 10hr broadband/TV outage within a day of each other.
Got home and tested, upload is now around 22mbps but my download is still all over, spoke to Tech support and a network fault in the area is causing it (tbh I think too many people online and it's congestion) but they now have a fix date of the 21st Sept.