Grizzer is right, most of the shops do change their staff every year, and if you are lucky you might find an instructor or guide who stuck around.
With Pulau Besar in mind, I worked at Watercolors the last several season, but they have changed management, this year I'm working at PIR resort with the nice sandy beach facing Pulau Kecil.
I won't on in this thread and put down or promote any one shop, but they do change and the management changes, so call or email ahead.
By the way diving is great right now, water temp is 30C too.
Have fun