Automated Invoicing QR-based System

Currently, each invoice request requires me to complete several steps. The guest sends me a message or calls me, provides their company details, which I then have to enter manually, locate the relevant reservation, issue the invoice in my invoicing software and send it by email... (Budget: €250 - €750 EUR, Jobs: API Development, Automation, CRM, Database Management, Invoicing, Mobile App Development, Payment Processing, Software Development, User Interface / IA, Web Development)