Help me unlock LTE BAND 20 (800MHZ) on mi 4i

Hello i wil try to unlock the Band 20 on the mi 4i.
but i dont have driver for the modem to open with the QPST tool.

did some one already tried to unlock this Band?
there many devices using the same prozessors an they can LTE 800 MHZ!

Hope some one can help me!