FDM download file issue

for the past week ive been trying to install the b2k patch for bf3 from origin and when it died as my connection is 250kbps, I used FDM with the falcon evo download.

This has taken me 3 days, but has left a file file instead of a rar file.

How do I convert file to rar as it should have downloaded as?

If there is no solution then im going to have to find some storage to do it on my faster school net. I hate origin  .