No international body has jurisdiction
Australia is a sovereign nation which means it has sole jurisdiction over its immigration policy. So, short answer: no international body has jurisdiction.
Who does have jurisdiction?
As it seems that the decision made is that the points you have been assessed by the Department of Immigration and Border Protection (DIBP) have not met the amount required in their invitation to you.
If you wish to dispute this decision the correct venues are, in order,
- Informal dispute resolution with DIBP - i.e. ask them for their reasoning.
- Formal dispute resolution with DIBP
- Review of the decision by the Migration and Refugee Division of the Administrative Appeals Tribunal
- A case in the Federal Court starting with the Federal Circuit Court and working your way up
- Appeal to the Minister for Immigration
The role of Australian Computer Society (ACS) and DIBP
You are mistaken in thinking that these organisations do the same thing: they actually have totally different roles in the process and as far as I can see they have both discharged them appropriately.
ACS is tasked with assessing your foreign qualifications and experience. They have done this and they state that your qualifications meet the requirements for a Developer Programmer. They make no statements that you will qualify for immigration, indeed their website specifically says:
Applicants must have a clear understanding of their personal visa requirements as set by the Department of Immigration and Border Protection (DIBP) or should obtain professional assistance from a Registered Migration Agent (MARA) before applying for an ICT skill assessment.
If you had received your qualifications at an Australian university and your experience was in Australia, this step would not have been necessary.
In a completely separate process, you have put in an expression of interest with DIBP. DIBP have invited you to apply and would have specified the points total you needed to meet.
With everything you provided, including ACS assessment of your qualifications, DIBP has assessed your application and found that you did not meet the requirements that they set for you.
You are not entitled to a refund of the application fee: that's whay its called an application fee and not a success fee: you pay the fee to make the application. DIBP have done all that the law required of them and, as a government body performing a government duty, your relationship is not contractual so you have no grounds to sue for it.
Where you went wrong
On the face of it, your self-assessment of your points seems wrong to me based on what you have posted.
For example, you have given yourself 5 points for having a post graduate Specialist Education Qualification - that is a Masters by research or a PhD in one of the nominated areas (Computer Science is one). ACS have equated your qualifications to a Bachelors degree - this doesn't cut it.
You have also claimed 5 points for the Australian Study requirement. Have you actually studied for 2 years in Australia?
On the other hand, assuming you have certified experience of between 3 and 5 years from ACS (I can only see 11 months in the letter but there may be more that you didn't post) you should have got 5 points for that.
You may be entitled to 55 points but probably not more than that.
It may not be too late to amend your application but you should hire a migration agent now to help you do this. However, if you don't qualify, you don't qualify and your money is gone.
Skillselect Terms of Service
The terms of service that you agreed to include:
That the Department of Immigration and Border Protection is not liable for the completeness or accuracy of any information provided by me where I do not provide information that is true and correct in all respects.
That the Department of Immigration and Border Protection accepts no responsibility for the completeness or accuracy of any of the information contained on or accessed through this website including SkillSelect and makes no representations about its suitability for any particular purpose. I should make my own judgement about these matters.
That to the extent permitted by law, the Department of Immigration and Border Protection is not liable for my loss, expense or damage arising from my access and use of, or reliance on, the information contained on or accessed through this website whether or not caused by any negligence on the part of the Department of Immigration and Border Protection or its agents.
As previously mentioned, you do not have a contract with DIBP and are therefore not protected by Australian Consumer Law and have limited, if any, access to negligence law. If you can demonstrate that DIBP were grossly or recklessly negligent you might have a case for reimbursement. However, they did tell you not to rely on anything they said and that you should seek your own legal advice.