Waiting for that client that never shows

It happens, we stand at the front reception wondering if everyone that walks by is that client we are waiting for, and sometimes they don't show up. We know sometimes things happen, but from our side, that time slot could have been booked by someone else. We noticed another salon in our industry posting about all appointments requiring a credit card because they were experiencing a lot of fraudulent bookings and while there is no way to determine if we've just experienced some no-shows or if they were fraudulent we have decided to require any new clients or those appointments for full sets to provide a 50% deposit.