VM rolled out a firmware upgrade to SuperHubs a little while ago did you get this?
Check in Super Hub Settings and scroll to the bottom of the page, mine is showing Software Version V2.37.01 If yours is showing earlier than this then turn it off for 30 minutes and then back on again. Check as above to confirm it has taken the update.
I am on VM's Up to 60MB and here is my graph:-
My Broadband Ping
Do check that you are still running the same IP Address as it might have changed with the 30 mins turn off. If it has changed then delete the Monitor and set up a new one. This is why I have named mine 2012-09-29 Onward to keep track after upgrading work in my area.