There is an overload somewhere on the circuit alright and the shop needs to find the trouble and place the correct size fuse back in. The trouble could be with the pump or wiring to it but the fuse most likely supplies other circuits also so the trouble may be elsewhere. If the fuse just blows when turning on the washer then the trouble is with that circuit. I suspect though that the trouble may be with some other circuit tied to the fuse but I could be wrong about that.