di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/ObjectManager/etc/config.xsd">
    <preference for="Magento\Customer\Controller\Account\LoginPost"  type="Gigya\GigyaM2\Controller\Raas\GigyaPost" />
    <preference for="Magento\Customer\Controller\Account\CreatePost" type="Gigya\GigyaM2\Controller\Raas\GigyaPost" />
    <!--<preference for="Magento\Customer\Controller\Raas\GigyaPost"     type="Gigya\GigyaM2\Controller\Raas\GigyaPost" />-->

    <preference for="Magento\Customer\Controller\Account\EditPost"   type="Gigya\GigyaM2\Controller\Raas\GigyaEditPost" />

    <preference for="Magento\Customer\Model\AccountManagement"       type="Gigya\GigyaM2\Model\AccountManagement" />
</config>