HR_Pramod - If a person is in service and avails EL, then he gets full/gross salary. Similarly, for full and final settlement, EL should be calculated per Gross/full salary. The above is per Chapter VII of the Factories Act.
The company's policy, procedure, or past practice does not have legitimacy over the Factories Act. Are you aware of any clause or court judgment to support payment of only the basic salary in lieu of earned leave? Request to share.
Regards,
Navin