Mr. Praveen, for 18th, it is regret, means you can't book from than to borivali. Better book tatkal from Jamnagar to Mumbai Central and change boarding point to Than - WL#21 SL, WL#6 3A, WL#2 2A. 3A and 2A have higher chances of confirmation.
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Upgradation is only done when all passengers aren't being able to be accommodated in the required class. It is done at random by the system. It is by fluke.