We are using Square API and trying to implement discounts while booking an appointment.
Is there any way to add a service with a discount in a catalog and add the catalog details in the booking automatically deduct the discount amount? or is there any alternative to add discount while booking an appointment using API?
At this time adding a discount to a booking isn’t currently possible. We’re constantly working to improve our features based on feedback like this, so I’ll be sure to share your request to the API product team. 
Is there any plans to implement this? We have been asking for it non stop. For those of us with a service business, this lack of basic functionality is cripling.
At this time there isn’t any updates on this feature. This is a popular feature request and we hope to have more for you in the future. 
and why not? its been years and you said its a “popular feature request”, what am i paying you for?