Hi Nenad, 

I know it's very late but I hope this can be helpful anyway. Our follow-up templates were created by our Odoo partner, but they are saved in Email Templates (remove Base Template filter). They required coding to produce specific information that we wanted to include such as customer name and unpaid amount. Your specific requirements of invoice numbers and total amount would likely require different code. I didn't create the code, but if it helps, this is what we use:

Hi Rakesh

Thank you. I tried that but the email in the templates under "Payment Reminder" is not the same as the one in the follow-up reports. Cant find the template for the follow-up reports.