Security Clearance for government job in abu dhabi

Hi,

I have got an offer from a government organization in abu dhabi. About a month back the HR told me to wait and not to resign from my present job (also in UAE but different emirate) until my security clearance comes. About a week back they informed me that the security clearance is rejected to my surprise. I have been living here since almost a decade and have absolutely nothing that i can think of for the rejection. However, during the process of security clearance last month i had renewed my existing visa in my present company which was almost going to expire. I later realized that my new company had applied for my security clearance after i had renewed my existing visa. Please note that i had given my old visa and EID details (though the number remains the same but the dates differ) to them. I contacted the HR and explained them this and they said that this may be the reason for the rejection (though the reason is unknown according to them), but they told me that once it is rejected they cannot re apply again. It is heart breaking as i have to let go off an opportunity that i worked so hard to get. I am not sure what i need to do now. Also the HR agreed that they should have checked with me before submitting the clearence form to the concerned. I have a very clean record of my status here in UAE from the time i started to live here. Not sure what to do now to convence them. Please if any one could suggest what i need to do would be of great help. Thank you and god bless!