Most likely the website was sold and the buyer decided on abandoning it
Their SSL certificate is expired, PayPal does not accept their payments anymore. Based on what the others are saying, I have avoided them. However, I tried searching for alternatives. Behold, bestonwardticket seems to do exactly the same thing and the reviews here on trustpilot are very good. Booked my return ticket, got a confirmation email, waiting for their business hours for the ticket to be delivered.