How do i contact nsi customer service? Phone/Email. Sales & Customer Service: 800.321.5847 Technical Support: 888.500.4598 [email protected] Fax: 800.841.5566. NSi HeadquartersWho is nsi distribution? NSI Distribution, is a corporation devoted to high quality products and customer service, which is reflected through NSI Distribution ’s long standing track record of professionalism and customer satisfaction.How do i contact ask nsi? Our digital assistant, Ask NS&I can help you to answer your queries all day, every day. Our webchat team will also be on hand from 7am to 10pm Monday to Friday and 8am to 8pm Saturday and Sunday, should you need to get in touch. Start a chat by clicking the blue chat icon in the bottom right of your screen.How do i complain about an nsi approved company? As a Certification Body NSI issues Certificates of Approval to organisations who work in compliance with recognised standards. Before complaining to NSI, you should complain formally in writing to the approved company. You should submit to us any evidence you have that corroborates and supports your complaint.