Well in order to do a better repair, with winrar you must have a seperate repair archive that will allow you to recover if the file is corrupt. You do not seem to have this, so repairing is out of the question.
This must be made when you are making the rar file, not after.
Also are you using the latest winrar, 3.20? if you are using the beta, then switch back to 3.2 and winrar isn't something you want to use a beta, like 3.30 build 5, with when making or extracting files with.
The only way you can really fix this is by getting the file again incase it was corrupt on downloading, if you can't find a non corrupt rar again then you might be sol.
Also, try running a test with winrar, open the archive and hit test and see if you find a corrupt archive.
Also, if it included and sfv or md5, then you can compare those files to the sfv and it will tell you which ones have changed, and corrupted.
http://web.utk.edu/~mmurph13/bssite/
That has two easy to use programs for such use.