Invoicing modul in fengoffice

We want to build a invoicemodule within fengoffice. This need to be integrated with the rest of the functionality in fengoffice. So sales reports etc is updated on sales generated by invoicing on customers. the invoicing mdule need a basic product field with the net price for the company if known, discount in % for the customer and sales amount. The discount need to be shown on the invoice, and also it should show the total discount amount given. It should be possible to import products in a excelfile, so productbase also need to be implemented here. When the company add a logo on feng, this logo also should be shown on the invoice. And also the company information they want to be show on the invoice head should be from what they have from fengoffice. They are able to when they create the first invoice to enter their own spesific invoicenumber. But after the first invoice are sent it is very important that they cannot do any cnahges on the invoicenumbers, it should just count further from the first invoice and be locked there. As the rules are quite strict here in Scandinavia, it is important the company are not able to delete an invoice or change the invoicenumber series after the first invoice are sent. If they need to credit a customer, it should be possible to credit the whole invoice or just certain productlines in the invoice and resend the invoice. It should be possible to send the invoice as a pdf attachment in email when it is created. And also it should be possible to send it as a link so it opens as a pdf in the browser. As 2 choices for the company. If the company send the invoice as a link, it should be a confirmation in that link, so if the custmer that recives the invoice and clicks on the link, it is confirmed by a green button and read on that time etc. This should then be visible on the sent invoice page. Where all sent invoices are, with total amounts. It should be a very easy way to send a reminder on the invoice after due date. So if you goto the invoicepage, you should have a checkbox for all invoices, where you can check one or more, and send reminder to those. And choose with or without extra fee and/or % calculated from due date for not paying on due date. It shall also generate an invoice journal on all sent invoices based on: month, period of two months or all months. or search for invoices on spesific dates, customers, invoice number etc. Basic search functions are of cource needed. It should be possible to then export this invoice journal by two and two months that are set from the start like this: jan-feb and so [login to view URL] journal should be easy ti import in accounting systems like mamut etc. We want companies that has expirience and referance work on this type of previous work. It is important that we can get a price and description based on that price. And a realistic date/time frame on when it can be finished. We also have more work in fengoffice and other changes there that we hope we can use the same company on.