By the sounds of it, he may be downloading as opposed to uploading.
Luke, if the 10 rar files indicate part1, part2, part3 etc. in the file names (eg *part1.rar), then my experience has been that all parts are needed before extraction can be completed. In this case, if you've downloaded the first several parts and the other parts are no longer available for you to download, then I think that you're out of luck
. No amount of renaming the files or joining them is going to help IMO. Of course, as always, I stand to be corrected