Dear Mr. / Mrs.,
I would be very grateful for helping me find a correct name for such work position:
It's a person who works for a wholesale (B2B) company. His main duties are: to communicate with regular customers who get in contact by phone/email/Skype; consult them with technical questions and help to find correct product; solve problems; take orders from them; write invoices; forward orders to warehouse for shipment; develop relations with regular customers; contact customers who who stopped buying; look for new customers; control payments.
Thank You in advance.