FORD dealers no nowt, how do they think the indicators flash then ?
I would check all the main earths at the battery and clean them up.
This certainly does NOT warrant replacing the fusebox.
Easy basic fixes.
The fans do indeed burn out wires, this is why most have replaced the ford wiring with standalone wiring as I have, and negatively triggered so fans can run after igntion shut off, and then also put a manual overide in if you want ?
You need to see if there is anything that is common to all the thigs affected such as earth point, fuse etc and start there, either that way or start at problem and work backwards.
If you have fuses blowing you MUST find out why, NOT just replace them.
heater could just be crud on the resistor wires/earth.
tabetha