Automated Invoicing and Collections System Development

We are looking for someone who can help us build and optimize our invoicing, payment follow-up, and collections workflow.

We have developed our own internal operations system for cleaning services, and we need help creating a scalable billing process around it.

Our ideal setup is:

When a service is completed, an invoice is automatically created and sent to the customer
All invoices should have 7-day payment terms by default
We need automatic tracking of invoice status (sent, viewed, paid, overdue, etc.)
Automatic payment reminders for overdue invoices
A clear collections (inkasso) process when invoices remain unpaid
Minimal manual work from our team
Integration with our existing operations system and workflows

The goal is to have a largely automated process where we can easily see which invoices are paid, overdue, in reminder status, or ready for collections without manually tracking every customer.

We would like recommendations on the best setup, systems, automations, and integrations required to achieve this.