what contact did you try? take a look at this topic from an FM906 build it mentions an email that could maybe get you through
also seems Flybike is B2B while Carbonda is D2C, so maybe the frame is available from Carbonda with another name?
I remember Peak Torque mentioning Flybike in one of his videos, maybe this exact model, and I was interested at the time but didn't went deeper...