All invoices are payable upfront in immediately available funds at our address. All invoices shall, without prior default notice, be automatically increased with a default interest of twelve percent (12%) per year as from the due date of payment of the invoice. In case of non-payment on the due date, evidenced by our registered letter of default, the amount of any unpaid invoice shall automatically be increased with ten percent (10%) with a minimum amount of € 24,79 as a default contractual increase. Any dispute of an invoice should be notified within ten days after the date of the invoice by registered letter failing which such dispute shall be not admissible. By accepting to use our services, the client accepts that the conditions above are being accepted by both parties as binding. A legal guarantee in an amount of € 53.396,27 covers our professional obligations under the conditions of the Royal Decree of 30 June 1966. Such guarantee may only be called upon after a notification has been sent to the debtor by registered letter with a copy to Toerisme Vlaanderen, Grasmarkt 61, 1000 Brussels (also by registered letter). Such letter and copy have to be sent within twelve (12) months after the execution of the works that has caused the debt to arise. All disputes shall be referred to the courts of Antwerp.