title: Booking system to take a deposit and then final amount at a later date
body: <p>This is more of a question regarding flow than code.</p>
  
  <p>I'm currently working on a booking website for a holiday home. I've implemented a booking system which currently takes full payment at the time of booking. This uses PayPal REST API. It works fine no problems code-wise.</p>
  
  <p>However my client would like the system to take a deposit when booking (20%) of the total. Then take the remaining amount later on (through the site). This seems strange to me and I've never used a website which does this so I'm not sure what the flow should be.</p>
  
  <p>The only way I can think of achieving this is that the user has to come to the website at some point in the future to pay the remaining amount. I could send them email reminders but it seems a bit awkward to do that.</p>
  
  <p>Has anyone done anything like this in the past?</p>