I used to work as a freelancer back in the days. I worked a lot for a customer became a good friend. At first I'd work on his projects, but this ultimately shifted to a model where I'd work on projects for his clients, I would bill him, and he would add his margin and bill the end-customer. It worked out great this way.

One day I got a call from him saying that our 'mutual' customer had an urgency job. They were supposed to do a national roll-out of a new payment system, but seemed to have forgotten about a bunch of legacy PoS systems that were still operational and couldn't easily be replaced. Because I was seemingly the only one that was still familiar with this particular system (I worked on it once in the past), the end-customer approached my friend whether I would be available to do this quick. This was in late November, and the rollout was planned for Januari. Because this end-customer is a government org, I realised we'd be guaranteed they wouldn't be working during the holidays (which, in my country is typically 2 weeks for Christmas and new-year's), so really we had only 10 days or so to get it done in time for their team to test it before they holiday shutdown.

I didn't feel like doing such a complex job on such tight deadline. So, I quoted a much higher rate than normal. I also quoted for a multitude of hours that I thought was required, due to the typical overhead that this large end-customer would surely incur. Finally I also added a retainer fee, because I knew that if problems would occur (likely on the last day before the rollout), I'd have to drop anything I was doing and work for them.

I got the job.

I worked feverishly to meet the deadline. I cancelled commitments on other projects, paid an extortionate amount for testing hardware and overnight delivered to my office, bought very expensive testing gear, signed all the NDA's required to work on PoS card payment interfaces, etc. I then worked basically round the clock for 10 days straight to get it done. I did get it done in time, submitted the code to the repository and fired an email to the team-manager that it was in fact done a day early. ...I was greeted with an auto-reply the manager would be on holiday till mid-January, which was the week that entire new payment system had to be rolled out nation-wide.

I wasn't feeling great about it, but my friend urged me to send the invoice for the work I had done, and also the retainer for the rest of December and January. This would allow the customer to write of the expenses in the current calendar-year. I sent the invoice, it was the most amount of money I'd ever invoiced, and I'd normally invoiced per month, this was for a mere 10 days.

December passed, no response from the supposed review team. I stayed on stand-by, declined any other work, stayed sober during the various new-year's office parties, always brought my laptop along, etc.

January came and went. Still no response from the code review team. The new payment system was due to be rolled out mid-january, but nothing had happened. The company had done extensive ad-campaigns beforehand announcing the new payment convenience for their end-users, so the only 'feedback' I saw were frustrated users on Twitter. I still felt bad about charging for the retainer.

This kept going. At some point I did stop sending invoices for the retainer. My friend always paid me in advance (the end-customer was notoriously slow to pay, though did always pay in the end), and I didn't want to cause him too much exposure.

To my knowledge, the software I wrote was never used in the end. To the public it was stated that the PoS systems were simply too old to be upgraded (not true, obv) and that they'd replace them 'soon'. It is now 4 or 5 years laters, the old PoS terminals are still there, sans the functionality I added.

By pure coincidence, years after the job I found out that an old friend of mine, who was also a freelancer at the time, was tasked around that same time by the same customer to do a code-review of a supposed PoS system upgrade. Without realising, he reviewed my code! He was under the same time pressure, and did the code review during Christmas to deliver the results on time before the national rollout in mid-January. He also charged a huge amount of money for it, was also paid, and also never heard about it again. At least he said he remembered being impressed by the quality of the code, and didn't find any defects. So that's about the best outcome of the project I guess.

My takeaway from this: If you are a freelancer, and a large customer wants something done in a hurry, charge more than you ever dared, don't feel bad about it. You'll find that suddenly there isn't as much of a deadline anymore. If the customer declines due to the price, you should be happy for dodging a bullet.