Response wrt to queries and enquiries

As the owner of an establishment I am dealing with guests and have to provide them with accurate invoices. I have been struggling to get hold of a Safarinow consultant for 2 weeks now.one cannot phone them and although they say they respond to emails within one day, I am waiting now almost 2 weeks to get a response. In the meantime I cannot provide my guest with an invoice, since we have queries regarding Safarinow's calculations .