In short, you can not re-arrange a cancelled MA.
The reason for this, is that we keep track of all cancelled MA's from the vendors in their contact profile, under related MA's.
This is because we want to keep a track of who could be wasting your valuable time, constantly booking and then cancelling their appointments. If we re-opened the cancelled appointments, then the record of how many have been cancelled wouldn't be true, and you could continue to get messed around by vendors.
However, appointments can easily be re-scheduled. All you have to do is go to the appointment, click the 3 dots on the right, and click 'Edit'.
From here you can easily adjust the date and time at the top of the screen.
Cancelled appointments can NOT be re-scheduled or re-opened, only booked appointments can.