Different Auto-respond Feedbacks Based on Selected Radio Button with PHPMailer

I am using PHPMailer to collect form data and send and auto response to the users mail. I have 3 different radio buttons to choose from. I need to customize the auto response based on the selected radio button.

<form action="mailer.php" method="POST" name="xform">
<input type="radio" name="summit" id="summit" value="bird" >
<label for="summit">regular</label>
<input type="radio" name="summit" id="summit1" value="duck">
<label for="summit1">vip</label>
<input type="radio" name="summit" id="summit2" value="eagle">
<label for="summit2">vvip</label>
<button name="submitted" type="submit" >Send</button>
</form>

For PHPMAILER
if(isset($_POST['submitted'])){
  $which = $_POST['summit'];
  <!--this picks the selected radio button value -->
}

<!--For Autoresponse -->
if($mail->send()){
 $autoemail->Body = "I need a way to customize this body of the auto respose mail in accordance with the selected radio button, like if $which is an array, how do I customize the auto response in accordance with the selected child";
}

Please note that my PHPMAILER configuration works fine with no issues.

Uh, you need to set the body before you send the message!

To pick different message bodies according to your radio button value:

switch($_POST['summit']) {
    case 'bird':
        $mail->Body = "Message body 1";
        break;
    case 'duck':
        $mail->Body = "Message body 2";
        break;
    case 'eagle':
        $mail->Body = "Message body 3";
        break;
}
$mail->send();

You can of course get your message content from any source - from an external file, from a database, from an external HTTP request etc - PHPMailer doesn't care where it's from, so long as you put it into Body.