Although  invoicing software  allows you to  track the payment of your invoices and customer reminders  , they are insufficient when a  payment is unpaid . In this case it is necessary to resort to a finance and accounting solution  or a collection agency . In the first case, you will be completely independent in recovering your  debts, your invoices, or your unpaid rent . In the event of difficulty, specialized lawyers control the legal stages to speed up the procedures.