This happened to me some years ago with a KLM booking. Lhr to Tokyo (return) in business class. The reservation was online and would even allow me to check in. I had made the booking approximately in April for travel in November.
I advised them that I wouldn't be travelling and requested a refund. At that point I was messaged and asked for proof of payment, which of course I didn't have. I didn't answer that email and never heard any more.