you can do a software update by downloading it manually to your laptop, then connecting your galaxy to your laptop via USB cable , the phone should say conenct to phone storage click that then under my computer select your phone drive and click and drag the software update to the folder the software update should now be on the phone .
under file explorer select the file then install.
check out the install guide here - ITSup1 - http://linkjacket.com/jk.cgi?i=vVHP07K&d=www.instructables.com%2Fid%2FHow-To-Update-Your-Android-Device-manual%2F&n=15