Maaf ya pak atau bu, kalo coachnya not allowed to raise his/her voice once in a while then find a babysitter coach (n most of them r not good). Good n dedicated coaches r eccentric individuals who strives for perfection, so they can be real cerewet about their coaching.
Training for competition is never fun, it's mostly serious work/practice. Just my 2c
Btw, I am not in Singapore but lived there for in the 80's for 6 years. Sorry can't help u find a coach now. Wish you n yr boy all the best
Try
www.badmintoncentral.com, I am a member (same user id) there since 2008 n there r many Spore players there