Develop app for Android and iPhone to locate clients

We rent equipment like bikes and so, and we need to have controlled via gps to our clients and the best solution is an app that can be installed on Android and iphones. Requirements: - It would be a multi-language app: Spanish, English and Portuguese - The app would have to run Android and iPhones. - The app would be able to locate the customer at all times, to know if he has left the area and to control if he is lost or go to collect our equipment or whatever matter - You would also have an SOS option, in case the customer gets lost or something happens, you could send your location and ask for help for whatever reason. - This app would send news and offers directly to customers, an easy way to send product offers to the customer base, who are already receptive to the product. - We want the client to see the app with its location on the map of our city, indicating where it is and what things are nearby. This map would have to be defined by us indicating that things want to notify that users are near and delimiting the areas that will be called of one way or another, so that if they happen of a Area to another, you would be indicated that they are located in x place. - We would like the possibility of sending any notice to the client also, for whatever reason, for example if it will delay in picking them or whatever, even open a chat to talk with him. - We want to have the possibility of sending to the app the photos that have been made doing the activity. There would be a control panel from which to manage these clients and their options. Since it will be necessary to associate the mobile number with a name or service contracted when it leaves its ship. To know to whom corresponds each location. The range of possibilities with the app is broad, and surely in the future they want some more options, so it has to be flexible for development. We would provide the design of the app. Let me know if you have developed similar apps.