HELLO EVERYBODY..I AM WORKING IN A PRIVATE COMPANY SINCE NOV 2001 UNTILL PRESENT.MY SALARY IN YEAR 2001 IS 25OOSR.I HAVE SALARY INCREASE EVERY 2 YRS OF MY CONTRACT AND NOW 2013  AM RECEIVING A TOTAL OF 4500 SR. BUT EVERYTIME  I RECEIVE MY SALARY MY BASIC IS STILL 2500 SR IN THE PAYROLL SLIP AND THE OTHER 2000 IS JUST BONUS.MY COMPANY DID NOT ADD MY SALARY INCREASE TO MY BASIC SALARY.HOW TO COMPUTE NOW THESE TO MY END OF SERVICE BENEFITS IN 12 YRS?