Symptoms:

Majority of HK people unable or unwilling to speak English.
HK spoken English among the worst in the world.
After 15 years of English classes (kindergarten 3; primary 6; secondary 6)
the majority of students can barely put a simple sentence together
 

Solution:

Fix the problem where it starts - at kindergarten, where children are taught incorrect sounds, phrases, sentences etc. In every kindergarten, let there be  Chinese teachers  for all subjects except English, and let there be a teacher  (either local or foreign) whose English is "native speaker" standard, for teaching English.  This English teacher would take the children for 30 minutes a day, for the three years of kindergarten, at the end of which time the children would be speaking correct English, after which what happens in primary and secondary school  would be almost irrelevant.