Thanks suzannal.
Actually this advice is what I got from Geobaby. Only that I wish to "migrate" here with my question for more information.
I am not sure what nanny service most HK people would be using.
By the way, Rent A Mum charges quite expensive: HKD160 an hour. A 6-hour break for myself would mean HKD1000.
To be frank, I don't think a lot of us HK people here uses nanny services. That is because there is usually a maid / grandparents we can fall back to.
Last time, when some of my friends came to visit HK with their baby, they asked the hotel to provide babysitting, and they charged around $50 per hour. But then, these are the housekeeping maids we are talking about. But then, baby is sleeping by then, so not a big problem.