The item is defective.
'Difettoso' — dee-fet-TO-so. Double the 't' sound slightly.
Use this to explain the reason for the return. A defective item gives you the legal right to a refund or replacement under Italian consumer law, so this phrase carries weight.
'Difettoso' is an adjective meaning faulty or defective. It agrees in gender and number with the noun: 'scarpa difettosa', 'scarpe difettose'. Under the Codice del Consumo, consumers have a two-year guarantee on defective goods in Italy.
È rotto.
It is broken.
Simple and blunt — fine for obvious damage.
Non funziona.
It doesn't work.
For electronics or anything mechanical.
Ha un difetto di fabbrica.
It has a manufacturing defect.
Formal phrase that strengthens your legal claim.
Italians rarely make a scene in shops. Even when asserting a legal right, tone stays measured. Raising your voice is seen as losing control, not as emphasis.