My son had a great birthday party before, i didn't find party planner but i find a Magician "Gor Gor"
to play magic and balloon twist for them and play games, it was fun! It is not a big co.... but i think he is good and nice!!! If you need details....let me know~ Hope can help.
I perfer finding a freelence magician or balloon man for the party. Just ask them if they can send you the photos or video for reference. Thousand of information can be found online. Try google it"balloon twisting hk or magician hk". easy?
But if you find a event planner, make sure you know who will be assigned as a entertaner. Normally these company just randomly send u a guy. Anyway gd luck