Your exports and foreign clients earn dollars; keep them that way. Eversend opens US-domiciled USD account details in your Nigerian company's name, so clients pay by ordinary ACH or wire and you decide when naira enters the picture. One receiving fee, 0.49% plus a fixed amount, shown upfront.
Because your client pays domestically in the US, the money never enters the SWIFT relay. No intermediary lifts a charge in transit, so the invoice amount and the received amount finally match.