I do also only call Level 3 now. I too have problems sometimes with slow uploads usually at night but my uploads go very slow where it is 0.03 upload speed. It does not happen every night and it is only brief about ten minutes but I know it is them messing around with the lines as it is not a all day, night thing.
The Level 3 techs say it is upload noise but only when I have slow upload otherwise when I call them when it is normal they say my signal is very strong. I had techs come but they don't do anything. They just check the line to my modem with a signal meter and everything is fine. Client relations is great as they gave me credits in the past and I just got a free month of service.