phone remote tracking software

I would like to track my runaway sisters location by sending a sms text to her unlocked iphone or by using bluetooth or any other method that would provide me with updated gps coordinates. I can narrow her down to a 10 mile radios but I need an exact location so that the cops can pick her up and bring her back home. I am her legal guardian, and have filed a missing persons report, and I would like the software or the capability to do this by myself using my phone or my apple computer or my boyfriends pc laptop. If I need to keep searching or if I need to use this app in the future, I want to be able to do so without having to download anything on their phones by actually taking physical possession of their phones. I would also like the ability to view the text messages sent and received or to turn the phone into a microphone to pick up what is being said in the room. My sisters phone is a prepaid phone with a bill under my name and an online account under my name, so I would be accessing my own phone. It is serviced under a company of T-mobiles called ultra mobile but I hope that won't make a difference. She has the phone on most of the time and has been posting on facebook, but if by chance she does have it off, I will want to know that the software or program works by using my friends cell phone numbers and verifying with them that the GPS coordinates I find are where they actually are. I will not fully pay for the product until I get this verification. If there are other suggestions besides the ones I've mentioned on how her phone could be off use to track her whereabouts I am up to paying for that software as well. It would be a required that if this software stops working for me within a reasonable time period that it be fixed by you and or updated. Please respond or [removed by admin] if you can complete this project for me within the budget.