The visible 3G written over the signal logo could be because the phone catches the 3G signal but the settings on the phone are not compatible with that. The problem can be solved by the customer care of your carrier and by applying manual settings over the same. The executive over the line will make you follow certain steps on your phone and you should call the customer helpline from some different number in order to do the settings side by side. On completion they will ask you for a restart and then 3G will work on the phone.