Dear Friends

I have Epica 2006 automatic 62000 mile. Few days the car off suddenly. When I started the switch nothing came and the fuel indicator did not move even the engine. I checked the fuses and I found that the Igni coil 15A fuse with ECM 20A fuse were blown. New fuses were replaced on the blown fuses and the car did not work. I replaced higher Ampere fuses 25A on both and the car work. Quickly, I took the car to the GM agency in my region. the agency fixed the problem my replacing the fuel pump with new one and the E.G.R valve also was replaced. When I took the car after fixing the problem happened again and I repeated the higher Ampere fuses procedure.
The agency informed me that the changed the set of wires and now everything is Ok. I drove my car to the work today but I am still affraid of the coming the problem back.
Can anyone help me with the right explanation for the above problem?

Thanks