Learn Italian: Se il servizio non funziona, faccia un reclamo. - If the service does not work, make a complaint.

Faccia is the formal imperative (command) form of the irregular verb fare (to do/make). You use this when politely giving an instruction to someone you address with the formal Lei. If you were talking to a friend, you would use the informal command fai (or fa').

If I wanted to replace un reclamo with the pronoun lo (make it), where would it go?

With formal commands, object pronouns (clitics) must come before the verb. So, to say "make it" formally, you would say lo faccia. This is the opposite of informal commands, where the pronoun attaches to the end of the verb (like fallo).

Why is "does not work" translated with non funziona instead of non lavora?

Italian has two different verbs for "to work." Funzionare means to function or operate, which is used for machines, internet connections, and services like in this sentence. When talking about a person doing physical or mental labor at a job, you must use lavorare.

Is fare un reclamo the standard way to say "make a complaint"?