Ford Fiesta 2008 Engine Management System Fuse ?

My granddaughter has a 57 plate Fiesta. Yesterday evening she stopped to buy fuel. Returning to her car, it wouldn't start. Breakdown service diagnosed a blown engine management system fuse. Replaced, the car started & she returned home. Went out later, key in ignition, all lights illuminated, turned key, car wouldn't start. Methinks it's the same problem, blown engine management fuse. Any suggestions how to resolve the problem apart from replacing the fuse each time it occurs?