I have been trying for days to get this contact form working on my site. I have rewritten it several times and tried many different things over the days. I just now tried putting it into a class structure. I am a beginner at best with php

class form
		{
			function validationFalse(){
					echo '<div id="sentMessage">There was a problem. Please check your form and try again.</div>';		
					return false;
				}
				
			function startForm(){
				//get the wordpress database information
				global $data;
				//if the submit button is pressed on the form
				if(isset($_POST['sendMessage'])){
					$contactName = strip_tags($_POST['contactName']);
				if( preg_match('/^[a-zA-Z ]+$/', $contactName) == 'false') {
					//if the contact name doesn't validate, call the error function
					$this->validationFalse();
				}
				$surname =	strip_tags($_POST['surname']);
				$email = $_POST['contactEmail'];
				$city = strip_tags($_POST['contactCity']);
				$messages = strip_tags($_POST['message']);
				//check to see if the variables are empty, if they are, just exit
				
					$contact = "Contact Name: $contactName \n";
					$contact .= "Surname: $surname \n";
					$contact .= "Email: $email \n";
					$contact .= "City: $city \n";
					$contact .= "Message: $messages \n";
		
				if(empty($contact)){
					$validation = false;
					echo "You did not fill out the form";
					echo $contactName . $email . $city . $messages;
				} 
				
					$subject = $data['contactsubject'];
					$headers = 'From: ' . $data['contactfrom'] . "\r\n" .
					'Reply-To: ' . get_bloginfo('admin_email') . "\r\n" .
					'X-Mailer: PHP/' . phpversion();
			
			
					$recipient = $data['reservationemail'];
			
					if(mail($recipient, $subject, $contact, $headers)){
						echo '<div id="sentMessage">Your message was sent</div>';
					}
				}
			}
		}
		
		$form = new form;
		$form->startForm();

It might look a little chopped up. Can you help me clean it up and get it working?

right now, it runs all functions when I press the submit button. Still calls the error message, and still sends the form and gives the success message