Thank you for the query, I may just have the answer for you. We seemed to notice that a few of our clients recieved this message after FileZillas latest update on 16 January 2015, where now the way you connected previously to your FTP host simply won't work after the update.
There are 2 ways we can try and go about trying to rectify this issue: (first ensure username/password are valid by browsing to ftp://ftp.domainName.co.za and see if you can list you directory via a web browser)
1 - We found that installing the previous version of FileZilla seemed to fix the issue and you should be to successfully get a directory listing once again. You can get this here - https://filezilla-project.org/
2 - Open the Start menu and type "filezilla." Click "FileZilla" from the list of results below the "Programs" heading to open FileZilla > Click "File," then "Site Manager > Select the name of the profile you would like to modify from the list of profiles on the left side of the dialog window > Click the drop-down menu to the right of "Protocol" and choose "FTP" and Encryption choose "Use plain FTP"> Click "OK" to save your changes. You will notice that this option has been set to SFTP by default in FileZilla client version 126.96.36.199
I am sure that one of the above solutions should assist you with the previous FTP issue you mentioned Have a great evening further.