End of Service Benefit for an Employee (Riyadh)

I am an expat, have been working for twelve years with a single company in Saudi Arabia. Recently I resigned from my job to leave on final exit and asked our HR manager about my End of Service Awards/Benefits, which he told me that it will be calculated on my basic salary exclude any other allowances such as housing and transportation allowance. As far as I know, End of Service Awards should be calculated on employee’s actual salary, which includes his housing, transportation, and other allowances that was fixed and paid regularly at each month.

Here is a detail of my salary that I have been receiving for last twelve years:

Basic Salary: SR Protected content
Housing allowances: SR 562
Transportation allowances: SR. 225
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Actual Salary: SR. Protected content

The Company is calculating my End of Service Benefits as below:

Employment Duration: 12 Years
Basic Salary: 2250 SR
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End of Service Benefits: Protected content SR

If I am not wrong, my End of Service Benefits should be as follow:

Employment Duration: 12 Years
Actual Salary: 3037 SR
_______________________________________
End of Service Benefits: Protected content SR

I am wondering if anyone here is expert on calculating ESB based on Saudi Labor law and had experience in labor court, please put some shade on following queries:

1. Which calculation will be correct between the above two?
2. If the company is trying to pay me less, how and where can I get some legal help on it?
3. Are there any particular documents to be avoided or sign up with my company before I take this matter to the court?
4. What kind of documents should I take with me in order to get legal assistance on this issue?
5. How long it usually takes when we go to a court/labor office to settle this kind of dispute?
6. What are the chances for me to get a court order in my favor?

I would highly appreciate any help to the above concern.