woocommerce plugin bugs

You need to correct how you call function in your class, if the function you want to use is in the class, for the add_action:
add_action( ‘woocommerce_account_wallet-endpoint’, array($this, ‘displayWallet’) );
add_action( ‘wp_login’, array($this, ‘walletOwner’), 99);

Replace all add_action or filter like this.