I also think it takes up to 14 days for the volt upgrade to be completed by virgin, so if you were on 500/600 before might not be implemented. Best way to find out is to go to hub settings and see what the Max Downstream rate is. If its 123000450 then its set to 1 gig. If it begins with 690 or the 500 variant or similar then you ain't on 1 gig yet.
If your hub is set to 1230000450 then it might be worthwhile doing a pin hole reset to make sure all the channels are up. Failing that id post your download and upload power/noise info for people to look at to make sure everything is as it should be.