Expert at Repairing FENDERS

This is Eddy, he´s a mechanic. He can repair everything about cars, while he whistles famous songs, played by Fender guitars.

He´s an expert at repairing FENDERS.

But I think he misunderstood my wishes concerning the car: I wanted the FENDERS of the mudguards to be repaired, not the mudguards to be repaired by using FENDERS.