If your customer accidentally booked onto a drop-in session instead of a course, then you can easily resolve this by asking your customer to purchase the whole course. This won't affect nor duplicate their booking on the drop-in session that they had already made by mistake, instead this will book them onto the rest of the sessions within this course.

If you need to action a refund or issue any credits back to their account for this accidental booking, then please check out our How do I refund or credit back a customer? article.