honda civic

Hello
I wonder if some one could help me, last night on the way home I noticed the speedometer needle on my civic 1.3i has gone down to zero while the car was moving, so in a lame atempt I decided to pull over, turn the engin off then try starting it again. I could not start it again, and noticed the fuse marked " Alternater/ SP" had burnt out. Each time I change this fuse it burns out and the same thing occures. Then sent it to the garage for engin diagnostics, at the garage they think it is the VSS "speed sensor" which we had changed, but the same thing keep occuring. Could it be the "ECU" or am I over reacting.