Can I stop a specific customer from making future bookings?

Not automatically, no. There's no setting that blocks a named customer from booking again — online or in-store — whatever you record against their record.

Marking someone Blacklisted doesn't block them

If Status markers are enabled on your store, you can mark a customer's record VIP or Blacklisted (Customers → open the customer → Status markers). This is a label for your team, not a rule for the system: a Blacklisted marker does not cancel their existing bookings, does not stop them making a new one, and does not touch payments or waivers. It's staff-only — the customer never sees it, on an invoice, an email, or anywhere in online booking.

That's deliberate, not a gap in the marker feature: a marker that silently blocked bookings would fail a customer at the counter with no explanation. It's built to tell your team something, and leave what you do about it to you.

What to actually do

If you need to stop a specific booking going ahead, you still have to act on it directly:

• Cancel the booking once it's made, the same way as any other cancellation.
• Contact the customer if you want to head it off before it's confirmed.

Marking the customer Blacklisted alongside this at least means the next staff member who opens their record knows to look twice — use the two together rather than expecting the marker to do the stopping.

See Marking a customer as VIP or Blacklisted for how markers work, and Cancelling a reservation for the cancellation flow.