Appointment App Development for Android

I would like it designed and built. 25% of total budget will be released after you show me working apk. No milestone will be created without seeing this 25% work and no payment will be given. Source code will be our property. Logo and other graphic designing work will be done at developer end in this budget only. Web services will be made by developer only in this budget. We will provide our own server. We are looking to develop one android application which could help people to take prior appointments before going to any mobile or any other service centres or other offices, Hospitals, automobile workshops, hospitals, restaurants etc. Same as they get prior appointments while going to passport offices. There will be an application on which mobile number OTP authentication using twiter digits and email i.d activation will be there. User will have to fill the form with these details. First Name and Last Name Present Address Permanent Address Current Mobile Number Working Email i.d Mobile make and model IMEI Number OTP Sent on Mobile Number Details of the Product in drop down. Main Category Electronics Sub Menu MobilesLaptops/Desktops TV ACOvenMain Category Automobiles Sub Menu CARBikesTwo WheelersMain Category HealthSub Menu Doctor's ClinicHospitalsBanks After filling all of the required details, a form will be downloaded with QR code and small fees will be paid and appointment will be given so that they could come only during their appointment [login to view URL] will ease the process of their services and they will not have wait there. An appointment letter will be generated and sent to user's mail i.d after filling all these details and same letter will be sent to concerned vendor's mail i.d and mobile number. After reaching to destination, both letters will validated by scanning qr code and process will be followed.