Apparently not - see click here (the rest of the thread is at the bottom of the page).
Remember, if both of these connections are coming over the same telephone line, then that line will be the bottleneck. If they are coming via two separate lines, as you have already foud out, you will need some pretty fancy hardware and software to perform the necessary load-balancing.
from what ive read it doesent seem possible to combine the connections. but would it be possible when downloading to use the 2 connections for differents segments. e.g. using download accelerator sorry if that made no sense, im kinda tires :(
I really don't understand unless you explain it better - so dump the one you're paying for, and up the speed of the free one. Why try an adopt a complex and expensive facility, when a cheap and easy route is available.