My web hosting company says there is something wrong with PHP code

My web hosting company says there is something wrong with PHP code

This is the PHP it suppose to connect to a contact.html page and then a
thank you page after afterwards.I just wanted a contact form. it wont
recognize files as .php.I did save it like that.
<?php
$name = $_POST['name'];
$email = $_POST['email'];
$number = $_POST['number'];
$message = $_POST['message'];
$from = 'From:you';
$to = 'me@hotmail.com';
$subject = 'Hello';
$human = $_POST['human'];
$body = "From: $name\n E-Mail: $email\n Number: $number\n Message:\n
$message";
if ($_POST['submit']) {
if ($name != '' && $email != '') {
if ($human == '4') {
if (mail ($to, $subject, $body, $from)) {
echo '<p>Your message has been sent!</p>';
} else {
echo '<p>Something went wrong, go back and try again!</p>';
}
} else if ($_POST['submit'] && $human != '4') {
echo '<p>You answered the anti-spam question incorrectly!</p>';
}
} else {
echo '<p>You need to fill in all required fields!!</p>';
}
header("Location: thanks.html");
}
?>