I have finally succeded in installing Marketpress Lite, the plugin Web invoicing and Billing.
I don't want to give the client the opportunity to pay via the invoice notification online. The rest of the notification is okay. I changed the email template to reflect this. Somewhere there must be coding that can be changed or deleted to remove the button "Process Payment" which appears not as part of the plugin it seems - I havent seen it in the email templates at least.
I have almost no experience so please give the simplest possibe solution.
thanks in advance