Got error ‘PHP message: PHP Parse error: syntax error, unexpected ‘Config’ (T_STRING) on line 19 [duplicate]

AH01071: Got error ‘PHP message: PHP Parse error: syntax error, unexpected ‘Config’ (T_STRING) in /pay/enot_end.php on line 19′

<?php

    include "enot/config.php";
    
    $MERCHANT_ID = Config::merchant_id;
    $SECRET_WORD = Config::secret_key;
    $ORDER_AMOUNT = $_REQUEST['amount'];
    $ORDER_ACCOUNT = $_REQUEST['custom_field'];
    $PAYMENT_ID = $_REQUEST['merchant_id'];
    
    $sign = md5($MERCHANT_ID.':'.$ORDER_AMOUNT.':'.$SECRET_WORD.':'.$PAYMENT_ID);
    $link = mysqli_connect(Config::host, Config::user, Config::pass, Config::base);
    
    if(!$link)
        die('Error Connect: ' . mysqli_error());
    
    if($sign != $_REQUEST['sign_2']) 
        die('bad sign!');
    
    $sql = "UPDATE `"Config::t_account"` SET `"Config::t_account_name"`="Config::t_account_donate"+".$amount." WHERE "Config::t_account"='".$ORDER_ACCOUNT."'";
    
    if(mysqli_query($link, $sql)) 
        echo "Records were updated successfully.";
    else echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
    
    mysqli_close($link);
    
    echo "Good";
?>