It is understandable that students get ill or an exceptional circumstance will come up and so I exercise a degree of judgement when enforcing my cancellation policy.

After the first no show, or an excessive number of short notice cancellations, I start asking for payment in advance of the scheduled lesson. This pre-arranged slot will remain reserved for the student. 

In the event of a no show, I will wait for 10 minutes, after which I shall leave the online meeting. If the student wants to join at any point during their reserved slot, I will remain available for that hour and they should contact me to let me know that they intend to join. 

Once a slot has been pre-paid for, if a student no shows, a refund for the scheduled lesson will not be given.