How long before booking do you ask them to confirm?
If the time they requested is more than 2 hours away, I ask them to confirm an hour before. If it's less than that, 1 hour before.
If it's within the hour I say "I'm going to send you a text with the postcode, please text me back and let me know what time you can get here." Then I send them the postcode of somewhere nearby.
I've probably doubled down by touring a well-known TW destination during school hols.
What's really annoying is that I moved my AW profile to Heathrow 2 days before I arrived to try to weed out the wankers, and set up auto response on my phone to say "please call back on Friday". TBF that auto response went out nearly 100 times and at least I haven't had 100 no shows