I'm not sure if there's a legitimate adult filmmaking class in Singapore (hmm business opportunity)
You can improve your skills by asking questions here, practicing and also reading filmmaking websites online. Plenty of awesome folks here who will give you good advice!
If you know where weaknesses lie, it's a good idea to offer your services on-set, in pre or post production. As a BTS cameraman, assist. lighting grip, clip logger etc. Nothing beats practice. Theory, classroom proctocols, can only get you that far and does not prevent you much from making mistakes in a real shoot with real pressures. Just like any other skills, practise makes perfect.
Also, you did not mention what aspect of filmmaking you wish to improve. The industry is so wide, no course can ever cover a fraction of the skills involved in creating a modern feature film.
Perhaps you can narrow down what you mean by "Advaned Filmmaking" to make it easier to point you the right resources.