3G not working on iPhone 4

I have an iPhone 4 locked on the 02.10.04 bb and unlocked with gevey SIM.
3G is not working at all, my phone is working on EDGE. My carrier is promissing more than 7mbps and I barely get 0.2mbps. They sent me the APN which I was supposed to write baseband and nothing else in the other fields. I also tried these methods:

-resetting network settings
-resetting all settings
-tried the unlockit website with custom APN
-hard and soft reset
-took my bicycle and tried connecting to 3G in multiple spots in my city

I didn't try restoring it to factory settings and setting it as a new iPhone because I'm not the first owner of this iPhone and I never set it as a new iPhone. I will do that when I'll come back home but I need to know if there are other methods that I should try. (also, please, avoid telling me to get an iPhone replacement or call Apple because there is absolutely no Apple store in my country).

I bought this gevey SIM from someone from a local forum. I tried his gevey sim in my iPhone with his carrier SIM (I noticed we're on the same carrier - Cosmote Romania) and the 3G appeared next to the carrier name but after I unlocked it on my iPhone, I only see EDGE, the 3G never turned on.

It is compatible because as I said, I know someone with the same device on the same network with a gevey sim and he is able to activate the 3G. I also made sure that I activated both the 3G and data roaming and I also have the latest firmware and the 3G is still not working but it worked once with that guy's sim and gevey sim on the same network. I'm only able to navigate through edge.