After several attempts I managed to get the firmware updated.
The latest version is 2.36
To get it to work I had to change several settings in the wifi config. Here are the commands that I sent to the Wifi.
1. Change the FTP server address to point to rn.microchip.co (IP 198.175.253.161 )
2. Change the FTP user name to roving (case sensitive)
3. Change password to Pass123 (case sensitive)
4 Save changes
5. Update firmware
6. Reboot
The above worked for me on 17th September 2012, but the server address seems to change without notification as mentioned in a previous post.
I found it worthwhile to download the manual which I have attached.