What are the easiest ways from Shekou, Shenzhen to Zhongshan please

I tried to get a bus from Shekou but the lady in the office said no and wasn't prepared top offer suggestions. I read on this website that it could be possible to go by ferry boat from Shekou directly to Zhongshan. I could also try to go by bus from SZ, Bao'an airport to Zhongshan but would like details of bus terminals at the airport before I attempt this. I've travelled around China quite a lot in the past but this journey feels a bit tricky. Thanks in advance Folks.