Mobile data connection stucks at EDGE (doesn't reconnect to 3G/4G network)


I have a problem with my Coolpad Mega 3.

Sometimes I loose fast data connection (3G/4G) and phone switches to EDGE.
But when I go back to area with 3G or 4G network, then it doesn't switch back to 3G/4G immediatelly. It takes a few minutes or hours or it will stay stuck.
Is there some way how to solve it? e.g. new firmware? This is bug thats makes Coolpad very uncomfortable to use.

I used iPhone 4 and Acer Liquid E700, and they react much much better.

I actually solved it temporary by
- entering Engineermode... means to call *20121220#
- go to MTK_Engineermode - Network Selecting - set e.g. "LTE only".

It will set mode globally, I guess. So if it will not work by the time, I will try to play with BandMode menu which is possible to set for particular SIM card.