limit on wallet

I have seen this method of setting limit on wallet . I apply this method but it doesnt work

//support limited functions
add_filter(‘is_valid_payment_through_wallet’, ‘__return_false’);
add_filter(‘woo_wallet_partial_payment_amount’, ‘woo_wallet_partial_payment_amount_callback’);
function woo_wallet_partial_payment_amount_callback($amount){
return (WC()->cart->total * 20) / 100;
}