Fix Mollie Payment Integration in Website

I have a fully functioning system and I am looking for an experienced developer who can correctly integrate or fix the integration of Mollie as a payment provider.

Current situation:

Mollie is already installed and basically set up on the server.

Payments are successfully processed and confirmed by Mollie.

However, subscription payments or payment confirmations are not being recorded correctly in our database.

As a result, the system does not automatically activate the paid usage period, even though the payment was successful.

Example of the issue:

A user wants to access the system for 30 days for €10.

Payment via Mollie → successful → confirmation received.

Issue: Our system does not correctly register this successful payment and does not activate the 30-day access.

This process works perfectly with PayPal, so the issue seems related specifically to the Mollie implementation, the webhook handling, or the database logic.

Looking for a developer with experience in:

Mollie API / Webhooks

PHP or the programming language used in the project

Database integration and debugging

Subscription handling (not required but helpful)

Goal:
To ensure full and reliable processing of Mollie payments, including correct activation and extension of the user’s access period.