I told you the solution to your problem before; the way I fixed my problem of the freighters sitting idle is that when you order him to 'Unload 6475 E-cells', he will load the station to 6475, then leave it. If the station drops by 1000 e-cells, he will come back, and drop off 1000 e-cells to top it up to 6475 e-cells (but won't empty the rest into it!). How you solve this (well how I did anyway) was to change the amount you want him to unload to the station's maximum e-cell capacity, 50000 for example; this means he will try to fill the station up to 50000 e cells, which will fill it over time....
I will be the one to take you down!