Possibly get it under warranty? Have you wrote Energica Directly? What year is your bike?
Otherwise any LED driver should work really, as long as the total power is at least what the headlight is, ie don't use a 5 watt driver for a 55 watt light assy.
Most places are only going to sell the assembly as that is probably how they get it. What made the driver go bad? corroding bulb holders? or something that's just going to take out the new driver as well?
Aaron