Are you sure that both numbers use the same units...ie, Kilobits per second (Kbps) vs. Kilobytes per second (KB/s)?
Realize that both are not the same, as a speed of 80 Kilobits per second is equal to 10 Kilobytes per second.
So if you specify a max upload speed of 40 KB/s, then it's possible that ABC is reporting the upload speed in Kbps.
Just a thought.