Factory Unlocked iPhone 4S wifi connectivity issue and APN setting not visible.

1) The Wifi disconnects frequently during the day and doesnt reconnects automatically. It has to be enabled and disabled via Settings. - We did spend quite a lot time over phone with iPhone support team Bangalore, India. As per their suggestion - we did iCloud backup , restore the iPhone to factory settings and restore the phone from iCloud backup - The wifi connectivicty issue remains the same though.

2) To overcome the WiFi problem temproarily , we got a predpaid 2G data plan , we did get a message that the internet has been activated but was unable to connect to internet even after restart. On Calling carrier customer care for iphone support - they informed to enter APN that was not availableeven after turning on 3G,cellular data and even data roaming for that sake. The network reset was suggested , but I have few questions before I do that. Does reset to factory settings not reset the network settings? If yes, Do I need to it again in order to get the page to at least use the 2G data?

I did go through all the posts in the forum listing the issue of low network and battery instability issues with iPhone factory unlocked 4S purchased from apple online US, but all the posts were preety old. Is nobody facing the issue after that?

Please help.