You can share your deal with clients and give them opportunity to make an Appointment through your social networks and private messages.
Vk.com:
You can place a button "Online Booking" in your community. How to add?
In Instagram:
Copy your direct link in section "Online Booking" and paste it in profile settings in section "Website".
In private messages:
You can copy direct link to the deal in chat with support service and send in private message with client. Client can follow the link and make an Appointment.