WinRAR has a built-in function that lets you bypass CRC errors. During the normal process, the extracted file is deleted once the error occurs. Right-click the RAR and select "Extract Files..." to open the general options window. Under "Miscellaneous," put a check by "Keep Broken Files." The file saves to the folder you specify, despite the CRC data. Many files will not work using this method if they are too damaged, but some will. You might be able to help also program RAR Recovery Toolbox. There is a demo version and you can verify whether this utility is useful to you or not. http://www.oemailrecovery.com/rar_recovery.html
Oh, Just in case you read this information. Might find something useful.
https://community.office365.com/en-us/f/172/t/269398