Need a quick google apps script writing, to take a gmail csv attachment, and import it into an existing google spreadsheet. The csv contains contacts, always the same column headings. Each attachment (they come every day) has to be added to the existing sheet, not a new sheet creating. Duplicates contacts (identified by email address) need to be removed on import.
This is a convenience script, not a commercial one, so value is relatively low, hence small budget.