Ok! Eureka! I think I've got it!
Quick background. I live in CPT and my parents in DBN. I have an ipad and iphone 3Gs and have had NO problem with downloads. Its important to note though that I have the Telkom 4Meg DSL line that is called their 'fastest - 4096kbps'. My parents have the 'Faster' which is 512kbps -or middle of the road. My dad has been unable to get the updates AT ALL since he got his equipment. Anyway i tried for 2 solid weeks to do the updates on both iphone and ipad to no avail. Kept getting error 9006. We have since discovered that DSL line that they have at home is not operating to even a 1/4 of its supposed 'faster' marketing. In fact when my mother tried to upgrade they said she couldnt because they dont have capacity to do so...yet they still pay the price! Anyway, when I got back to CPT i updated both my dads ipad and iphone in 15 mins and with no error. Thats what made me think its a speed and line error for the area you live in. You need to check if the line is stable and fast enough to do the update. Check that here [if you are in SA]
http://www.telkomsa.net/ and go to speed test. My download speed is 1.68Mb/s. So if you want the update, do it in a place that offers the fastest DSL, its a Telkom issue. Hope this helps