We've used ToursByLocals to book guides all over Europe and have been pleased with the experience. In Rome, our guide was named Sylvia. She was excellent. Here's the number I have saved for her. +39 334 7814063. I'd try to reach her via text or on WhatsApp. She didn't pick us up at the port, but she may be able to arrange that or put you in touch with someone that provides that service.