When you book for a term of lessons, you have reserved and paid for that time-slot for the term, and you take the risk that you may or may not be able to attend for all weeks of the term.
Dave is under no obligation to re-schedule or make up lessons you miss due to life, illness or misadventure.
Make-up lessons will be given when Dave cancels – and only at times and dates within the normal teaching schedule (weekdays before 8pm) or can be arranged at any mutually agreeable time.
The lesson is considered to have been given if the student misses the scheduled make-up lesson for any reason.
There are no refunds for missed lessons, ever.