What are your interests? If at this point now, your points does
not enable you to get into a course you want, maybe you can
consider re-taking your "O" levels as a private candidate.
I feel that it's better to waste 1 year to re-take and hopefully
with a more serious mindset, you can get better results, then to
waste 3 years in a Poly, getting stuck in a course you totally
hate. If you hate what you study, you won't get far anyway.
Then again, do not underestimate the "unpopular" courses in the
poly, cos those courses have less graduates, which might make your
cert more valuable when you look for a job in the future.
Good luck!