Availability is calculated by VikBooking by taking the number of available rooms of a certain Room Type on a certain date, and subtracting the number of confirmed bookings made to those rooms on specific dates.

1. Create a new booking from VikBooking
2. Reduce the availability from VikChannelManager

You can create a booking in VikBooking from your website, or you can use the “Calendar” page. Either way, the booking will occupy the room on specified dates, therefore reducing the facility’s availability for the dates of the booking. If you have enabled "Auto-Sync" on both VikBooking and VikChannelManager, the new availability will be sent to VikChannelManager, and therefore all channels

Reducing availability from VikChannelManager works pretty much the same way. You can do this by accessing the “Availability Overview” page of VikChannelManager, then selecting some dates and reducing their availabilities. VikChannelManager then will ask you for which channels you wish to send the availability reduction. If you pick the "Website/IBE" option, VikChannelManager will create fake bookings on your website, therefore reducing availability. Checking any other checkbox will send the new availability to the respective channel, lowering it on their end as well.
Please note: any update made on VikChannelManager will remove these changes, and the availability will return to its regular value.

To increase availability simply remove those bookings that are reducing its availability. If that is not possible (because the availability has been reduced by a client's booking), you may not increase the availability of that room type for the selected date.