XFileSharing Pro - Problems Uploading Big Files

[bbgnetwork]

I am experiencing a very problematic issue when people try to upload large files (500mb+++). The progress bar just freezes most of the time at a random percentage, and the upload does not complete.

I am not really sure at all what could be causing big uploads to simply freeze before being completed. I have email SibSoft but they don't seem to want to reply

Any help would be much appreciated!