Service Center Cannot Replace Rear Dual Camera Properly ASAP!

Hi everybody, My HTC M8 fall from 40m height, my screen was broken and camera not workin. As I am russian and my family lives there, I gave them my HTC so that they can take it to service center and get it fixed. They managed to fix the screen but not cameras, as they didnt know where to order them. So while being in Spain I ordered both cameras and then brought them to Russia and gave to service centre with the phone. So, here comes the problem, they disassembled my HTC took the metal casing where both cameras were and connected the new big one but connected without metal casing-hanging. So the problem is that it doesnt have AutoFocus now. More problems come now, when you connect small camera you cannot enter camera app and make photos( with only big one you can). So we took it to another center where they said that there is whatever problem with some plate or something and they cannot fix it. So its now laying on the bookshelf disassambled.

So my questions are :

1. Can I use it with only one big camera?

2. Does second camera affect autofocus?

3. If not, can it be fixed by mounting it to the original metal casing( which should hold it in a fixed position alowing micro movements for focusing, am I wrong?)?

4. Could it be some plate which connects small camera that doesnt allow second camera to function properly and what could it be?

Please Help me ASAP if you know anything about situation like that.