I used a local minicab company once to get to the airport to catch an early morning flight from Stansted. Found their website using Google, booked and paid online. Called the office the day before travel just to confirm the booking and they said it's all good.

The next morning I get a call from a rather rude operator - just minutes before they were scheduled to pick me up - telling me that I haven't paid the full amount for the ride. I told them that I booked using their website and paid online with PayPal. He replied that he doesn't know why the website didn't show the correct amount but if I don't pay an additional £30 to the driver they won't give me a ride. I agreed because I just wanted to get to the airport asap and not deal with finding another company.

The lesson I learned here was: I don't trust minicab companies to be able to deal with the tech behind something like Uber. Of course, this was just one bad experience with a single company but it did leave a bad taste in my mouth.