MeiLing as far as I know the world I am in if the money was paid by credit card, I can always dispute the charge.
Only reason I would be disputing the charge would be, if you look at the initial post when this person did post here, most of the dive instructor and dive op asked this person to take the hit, shut his mouth and just do away with it, then I recommended that diver dispute the charge with credit card company and again the dive op and instructors showed sympathy that all credit card would do is take away money from dive op and refund it to customer.
If this dive op was honest then they could had give couple options to the customer like either full refund or take a cancellation fee and refund the balance, or say we give you store credit whenever you want to come back we will work with you.
I am not a dive op or a instructor and I am only arguing from customers prospective, why is only customer supposed to take hit and dive op gets special consideration.