So I've officially been in business a little over a year. One of my first signed contracts has their wedding coming up next weekend. Their final payment was due this past Saturday, however they've only paid half of the final payment. We're a small operation. The final payment is needed to get their food and china. We sent a "hey where's the rest of the money" email this morning. Should we establish a deadline, or what? Any advice on how to handle this, as I'm sure it will happen again, would be great. Thanks.