I'm sorry, but your post is not very helpful. Obviously you know that WinSCP supports transfer resume. It may just not be working for you for some reason. But you need to give us more details. So what happens when WinSCP tries to resume file transfer? Log file would be useful. What's worse in 5.0.5?

I've been using WinSCP for about 2 years now and yet to see this feature working. Almost everything about this program is great except this one most important thing. It still cannot resume transfers. Why? I don't know. I even written a program myself to keep track of its "resume transfer" dialog (whenever it pops up) and sends a WM_CLOSE to the dialog to help it resume the transfers. I don't know why it still cannot do that by itself. I'm using 4.3.6 right now. I tried to upgrade to 5.0.5 but it made things worse (not to mention resume transfers were not working again).