There has been a slight improvement on my connection as you can see on this graph... but I've had 142Mbps at peak time with 9 ping which is much more like it. It might just be a fortunate time, or a few of the upgrades may be taking place.
I was told that my issue would be resolved by April 19th and, having read through the forum for some time, I wasn't expecting it to be a resolved.
However, I would like to give credit to Virgin Media, as they did what they promised - thanks! I did a test on the 20th and got a great speed. It has been very consistent in May and it's back to being a fantastic connection. So there can be an ending in sight for those with a troubled connection. I have my fingers crossed it will remain strong for a long time!