Upstream doubling will come once your area can support it - or rather when VM deem it can support it as the chances are upstream doubling will cause big problems imo because the local networks are incapable of supporting higher speed and quantity of upload without considerably more work than VM are likely to do.
You're not alone ldavey with mild frustration. I got changed to 60mb yesterday from 10mb down, 1mb up, and was also surprised by my 2.9mbps upload and not 6mbps. But yeah, I was told the same thing by someone. He called it channel bonding. He said this:
"Channel bonding is where they use multiple upstream or downstream channels to allow faster speeds.Your hub at the moment will most likely have 4 or 5 downstream channels and 1 upstream. When the bonding is complete you will have I think 4 upstream channels. They are in the process of upgrading the equipment. I got an email regarding it the other day and I'm sure it said it was coming at the end of the month but not sure. Also because it is a nationwide upgrade it could be done 1 area at a time so I wouldn't hold your breath for it happening anytime soon, lets say quarter 4 of the year. If it happens before then its a bonus i guess"