Meg is egoistic guy who actually do not want to accept that the mistake is from Apple's side and not from carrier side.
Same problem I was having in motorola, the device always get connect to more stable network.
Say for instant, networks usually represent themselce as "out of 5 points", that means they are available as 1/5, 2/5, 3/5, 4/5 and 5/5.
Now, if 3G network that is abailable in my area is 3/5 and the 2G network available in my area is 5/5, apple/motorola phones will be selecting the better one that is 2G network.
On the same time and place with the same carrier sim, my MI phone which has option to select only 3G/WCDMA mode will keep connected to 3G network and the speed will always be better in MI phone only as its connected to better network.
Now this shows that it completely depends on phone that which network to stick to and keep connected even after getting lower signals but hey, lower network newer affect the internet speed.
Byt if device gets connect to 2G/GSM, internet speed is very very very slow.
Now this is the problem in our India.. I hope Apple guys read this and fix the issue as it is very possible to fix this just by giving out a simple update to their current versions.