You have stated you are gathering opinions - here’s three.
As a potential customer:
There is no way in hell I’d pursue or pay for any type of instruction with an instructor who can’t or won’t commit to a schedule, whether it’s for me or my family members. Your services, however good they may be, would be excluded from my decision matrix based *solely *on that.
As a parent of a young child who is still figuring out activities she likes enough to take lessons in (dance, gymnastics, karate, etc.):
I’ve had multiple opportunities over the past few years to **request ** a refund (note the verbiage) for lessons purchased in a block, but not fully completed due to a loss of interest. With one exception, I have received that refund quickly, with no drama, threats of social media firebombing, or references to “fine print” or other legalese. The lone exception was a studio staffer who was unwilling to issue a refund; when we inquired directly with the studio owner a couple days later, we had our refund *and *an apology within 10 minutes.
As a customer:
IDGAF what makes your bookkeeping easier re: refunds. You state you’ve only had 3 refund requests in 5 years - it doesn’t seem like too much trouble for you to change your bookkeeping once every 1.5-ish years in order to maintain your reputation within your conurbation.
Issue the refund ASAP, and be thankful you have enough customers who are willing to “shotgun” their lesson scheduling, or lack thereof, for you to continue having a viable side business.