CSV IMPORT SCRIPT FOR WHMCS

We are a hosting company and currently use Clientexec but will be moving to WHMCS. We need to import clients, contacts, domains, and more to WHMCS. We require a WHMCS expert for this job. Our current billing system (clientexec) has an option to export customer data as a CSV such as : id Status Date Created First Name Last Name Organization Address City State Zipcode Country Nickname Email Phone VAT Number Domain name Username Where did you hear about us ? Receive Email Announcements We can also export invoice data as well that will need to assigned to the correct customer. We are looking for a custom tool to import these values into WHMCS (like: [login to view URL] Requirements: - The tool should have the possibility to import all the data from our current billing system into WHMCS. - The tool should have an option to synchronize / update the imported data because it will take some months to move all customers to WHMCS and the data should be updated in the months we are moving. - There should be an option to select which data should be imported in WHMCS and to select the client for each type (invoice, hostingaccount, domain).