Service company looking for invoicing software with order processing

We are a service company with two business areas. In the first, we provide services that are invoiced, in some cases with additional purchases, on which a surcharge is levied. In the second, we receive invoices from customers, which we settle on their behalf. This is a transitory item, which should also show whether the invoice has already been paid. We charge the customer monthly for this service based on the number of invoices settled.

The software should therefore support the following tasks and functions:

• Generating invoices to customers
• It must be possible to assign invoices that we settle for customers to the respective customer (comparable to a billing service for doctors)
• It must be possible to see whether and when the invoice was paid and when the invoice was processed
• Customer administration (optional)

1-3 workstations are planned.