It is true, there is an appeals process, but please do not pay the $500 and go through the formal appeals process. It is a scam! An even bigger scam than NNAS is itself. If you appeal and they find a different result, NNAS refunds the cost of the appeal. This sounds great at first, but, I have read through the fine print and the way they have it worded, it is too easy for them to say that they reviewed your documents again but there is no change to your Advisory Report. They can easily blame it on the documents sent by your school and say that maybe your school is the problem because they didn't send enough information. Then you will have lost $500 and you are no further ahead. I don't know anyone who has positive changes as a result of the appeals process.
This is what I recommend instead:
Call NNAS and ask (demand) to speak to the person that signed off on your Advisory Report. There should be a name at the bottom by the signature. If Customer Services tells you that is not possible, say that you would like to speak with their Manager. Be polite and professional but persistent. They will likely say they will have that person call you back. Ask for their email address and send a follow-up email, if they give you the person's email address (they likely won't but it's worth a try). If you do not get a call back in 3 days, call again. Repeat until you get to talk to who you need to talk to. Explain that given your situation with your Canadian education components, you would like them to have another look at why the NNAS assessment is not catching Canadian curriculum content. But be very clear that you are not expecting to pay for this, since their assessment is designed to pick up on Canadian curriculum content.
If you are unable to have any changes made to your NNAS Advisory Report, continue on with your application to the licensing body. Ensure that the licensing body also has your Canadian syllabi and education information in your file (it should get forwarded along by NNAS when they send your other information to the licensing body). Write a polite and professional letter to the licensing body stating that you are concerned that the NNAS assessment did not take note of your 1.5 years of Canadian education and ask that they review your file themselves. NNAS is only the first pass through your application and licensing bodies are the second. There are some people that once the licensing body got their full file in their hands, were able to move to the next step because they were considered to have met the education requirement. Licensing bodies are not bound to the outcomes of the NNAS assessment. They can overrule and I think in your case, it is worth pointing this out to the licensing body. They need to know that the assessment they are using is missing some important things. The main thing is to stay on top of it and keep advocating for yourself.