Publication dans Vinh, Nghệ An Province, Vietnam

Hi, can someone please advise? We arrive in Vinh by air, and we'd like to travel to Đồng Hới from there. We land at 11.10 am on a Sunday, so we will miss the train. How frequent are bus services between the 2 cities, and where can you get on these buses? Are there any other alternatives? How much would it cost to hire a car and a driver to take us to Đồng Hới? Thanks!