I have gone through your description and got a pretty much idea of what you want. I can assure you for a complete professional work in given time line.
Relevant Skills and Experience
List of my skills is following as;
1. PHP, Codeigniter.
2. Wordpress, Magento
3. API Integration, Plugins integration & Customization
4. MySQL, Oracle
Proposed Milestones
₹1250 INR - Paytm Payment Gateway
I am available to book my time for you to start work immediately and I also provide 2 months support after complete project. Looking forward working with you for a long term.