Urgent SunPay Integration for Android App

I urgently need a professional to integrate SunPay Payment Gateway into my Android app. Gateway is already working. Just need to fix few integration related issues.

Key responsibilities:
- Establish a fluid and secure payment process through the SunPay system
- Ensure optimal user interface for the payment process
- Execute rigorous testing to guarantee a flawless user experience

Ideal candidate will have:
- Extensive experience in Android app development
- Proficiency in PHP, Java and Kotlin
- Proven record with integrating payment gateways, particularly SunPay, into Android apps
- An ability to work under a tight deadline. This project needs to be completed ASAP.