Developer Needed to Fix Recharge Pending Issue in Auto USSD Recharge System (Node.js, PHP & Android

We have an existing auto-recharge system built with Node.js, PHP, and an Android app that performs automatic USSD recharges. Some transactions remain in Pending status even after successful recharge. We need an experienced developer to review the codebase, identify the root cause, fix the issue, and improve overall system stability. Experience with Android automation, APIs, webhooks, and backend systems is required.