I maintain an instance of FOSSBilling and have run into two long-standing problems that affect both Stripe and PayPal: invoices are marked as paid, yet the linked services are either not renewed at all or are renewed several times in a row. The full context is on GitHub—issue #3105 and pull-request #3170 (closed but still unsolved). What I need • Diagnose and eliminate the root causes of these payment-callback bugs for both gateways. • Ensure that, once payment succeeds, the corresponding service is always renewed exactly once—no skips, no duplicates. • Submit a well-documented pull request against the main FOSSBilling repo that the core team can merge without further edits. Environment & stack FOSSBilling is PHP-based, uses MySQL, and communicates with the Stripe and PayPal REST APIs, so solid experience with PHP, webhooks, and Git/GitHub workflows is essential. Acceptance criteria 1. Reproduce the faults described in #3105 on a clean install. 2. Provide unit or integration tests that fail before your patch and pass afterward. 3. Demonstrate, through logs or screencast, a successful single renewal for both Stripe and PayPal payments. 4. Create a pull request referencing the above issue numbers and outlining your solution. There are no consistent error messages in the current logs, so you will likely need to add temporary debugging hooks or increase logging verbosity while tracing the problem. If you have already worked on similar billing-gateway fixes—or better still on FOSSBilling itself—let me know.