So, I just kept trying - all of sudden my X3 download worked on Tuesday night.
And then after about 20-30 attempts at downloading the M2 image, it worked as well. Completely random, just all of a sudden decided to work.
I found that when I did the download and the verification failed, there was no point re-running the verification as it would always fail on the 2nd/3rd/4th etc. attempt. The only way to move forward was to scrap it and start the download again
But, persistence paid off - eventually it worked and the M2 was updated today!
Cheers,