WhatsApp chatbot API

I am looking for an experienced bot developer specializing in WhatsApp Business API, with the ability to integrate with Bit API or PayBox API for automated payment processing. The system will allow residents to process payments smoothly, while automatically calculating and distributing a commission.

Requirements:
-Previous experience in similar projects (please provide examples).
-Availability for support and improvements after the launch.
-Recommendations from previous clients (preferred).

Please submit proposals including:
-Estimated development time and cost.
-Examples of similar projects.
-A pricing proposal for ongoing monthly maintenance (if required).