there's Dr. Hii at Khatib Central, my first two appts with him then I change as I don't feel comfortable with him and find him expensive, however, there's another mummy here who signed package with him. You can just walk into Dr. Hii clinic and make appointment.
There's Dr. Chen Lin Han at Chong Pang, a friend recommended me to him and he's very popular, very crowded. he has two clinics, one in Chong Pang, second one at MT A, so give them a call before you make appointment.
I'm seeing and have signed package with Dr. Don Wong whose clinic is at Admiralty MRT station further up after Macdonald's.