Hello there, First off, I know that many people ask this question but I still cant seem to find an adequate solution. Here is what I need to setup: I have 1 employee, 1 location and 1 service The service will be offered at 1pm, 5pm and 9pm a service can only be booked by 1 person at a certain time, so you can only have 1 booking at 1pm, only 1 at 5pm and the same for 9pm on any given day. So my services is set for a duration and slot step of 240 minutes, client wants 4 hour slots and the daily limit is not set to anything, the connection is that 1 employee & service & location is available from 1pm till 11pm at night and the slot is set to 1 here. and the busy slots are calculated by worker, service and location in the settings page. But it still allows for a service to be booked twice at the same date and time, how do I prevent this so that only 1 appointment is available at a time, so 1pm accepts only 1 appointment and 5pm only 1 appointment and the same for the 9pm slot. Clearly I must be doing something wrong but please guide me in the right direction to setting this up.