eBay! Get a replacement ZR-6!
This is, by far, the best and cheapest option for your audio needs.
I love how silly people sound when they say "I just want something with Bluetooth!"
Sorry, not meant to offend really, but you clearly don't know how Bluetooth works.
It is designed to go from your head all the way (3 feet or so) to your phone. Or perhaps to your car radio. Get crazy and maybe five feet to your computer.
It doesn't cover your ENTIRE HOUSE. You don't just get a magic Bluetooth box which allows for audio to be played back from anywhere.
If you want to play your phone from anywhere in your home, you need a Wi-Fi solution that connects to your home network and then can tie into your whole-house audio system. Something like a Sonos Port or a Bluesound Node.
But, at the base, your in-room controllers allow for local source audio select, with multiple sources available to the system. Local in-room volume control is also available from the keypads. Yes, phone control would be a nice additional feature, but you typically do want to be in the room when you adjust volume inside the room. Plus, you don't typically want to have all rooms playing at the same time necessarily, which is what the Niles allows as you choose.
A replacement unit, for under $200, is designed for exactly the type of use situation that you have in your home and for the money for a used unit, it's a steal.
If you do want something with integrated phone controls with volume to each room, then you would need to look at something like a HTD system...
Whole-house audio systems you can install yourself and control with smart phones and tablets. All HTD systems include a 30-day guarantee and 5-year warranty.
www.htd.com
Those start at about $1,000. Not sure I'd want to pay that much for adding phone controls to a fully built out system.
I will add that I've added phone control using Crestron for about $400 to systems of this nature in the past. Nothing crazy, just basic "Select a room", select a source and adjust volume for that room controls. It seems easy enough, but you have to have a device which supports it, and a device like the ZR-6 does support that type of activity. Literally only took me a few hours to program a super basic interface for it, but has worked well for my client for several years now and gives them the iPhone control they wanted.