Four no-shows on a Saturday is 16 covers. At a 40 cover restaurant that is a tenth of the night gone, with the staff already rostered and the fish already bought.
Most of them are not malicious. People book two places and forget to cancel one. Or they booked three weeks ago and the date slipped their mind.
The fix is boring. The day before, around 11am, every booking gets a message. 'Table for 4 tomorrow at 7.30, still coming?' with two buttons, confirm or cancel. It goes by SMS or WhatsApp, whichever number they gave.
Confirms are marked in the diary. Cancels free the table, and if you keep a waitlist the next person gets a message straight away. The ones who do not answer by 4pm get a second message, and the ones who still say nothing are flagged on the sheet so front of house knows to hold the table for fifteen minutes and no longer.
When someone does not turn up, nothing happens that night. Two days later they get a short note. No telling off. Something like 'we missed you on Saturday, here is a quiet Tuesday if you fancy it'. A fair share of them book again.
This is the kind of thing we build. It runs off your booking diary, OpenTable, ResDiary or a Google Sheet, and the messages come from your number.