Your results belong to the better type. But it is not good enough to go to JC.
DPA.
The admission excerise is just to cut the adminstration work. It concerns more for the school adminstration.
Application with appealing or CCA are for those people who cannot make it.
You can always appeal to change schools and courses.
DPA ("Direct Polytechnic Admission") gives O Level students a priority over other students applying through JAE.
So if you apply for DPA, if you get shortlisted, you will be called down for an interview and some courses may require you to sit for an apitude or skills test.
If you are accepted, it means you already secured a place in the poly's course. So as long as your O Level is within the course's and the DPA's minimum entry requirement, you will get a place in the course. Certain polytechnics may have different crtieria and requirements for DPA students, some may require students to attend camps and extra lessons before school starts for other ordinary O Level students.
For example, if the cut-off-point is 10, and you get 16, you will still be able to secure a place as long as you fulfill the minimum requirement for DPA.
Check up SP's DPA system.