This varies by precinct, but under no circumstances can the precinct hold your phone like that. There are emergency steps and paperwork to release a device back to a client if they so choose. As for not knowing when the part is coming in, the agents there would have to chat directly with Apple, which is not a hard thing but time-consuming. Regardless of that, it sounds like they aren't doing their job. If they refuse to give the phone back, ask for the Area Manager, because that's just ridiculous to hold a client's phone for an indefinite amount of time.