Hi there!
I keep reading this thread passively. I can't say I understand the tough time you are going through right now, but will tell you not to give up if you have got everything right. Pursue all measures available with prudence and resources available with you.
There are cases, where people have got PR with reference letter submitted similarly as yours. Hence, I can only suggest few things as below:
1. Double check everything that you have submitted related to your work (I know you would have already, however no error before going for an appeal).
2. Particularly check that job duties match with your NOC and you have the required no. of hours of work-exp. (You can prove this in several ways). Your letter that you submitted, from your colleagues / seniors - check if you can get them notorized. Also, if there are more than one colleague / seniors at your work place who are willing to write the same letter for you, get that as additional reinforcement to your letter.
3. Please research a lot, definitely take advise from an authorized immigration lawyer and ensure there are no loose ends - before you go for appeal. Below is just one link I can suggest, you might have to surf a lot on such forums to get a clear picture.
https://www.canadavisa.com/canada-immigration-discussion-board/threads/post-e-apr-process-and-common-reasons-for-rejection.510587/page-112
Good luck, and know that whatever happens, happens for good, irrespective of what happens with this application of yours.
Godspeed!
PS: I am a 12 Sept.2019 AOR, PNP-O, CIO Sydney, family of 4, applying from India, got the ITA after 5 years of waiting and keeping the faith that whatever happens next, it can only be for a greater good!!