Yes I have. However there are delays if it went down the manual route - you can tell which ones are manual since they don't show a refund quotation before you click to confirm cancellation.

In terms of refunds (i.e. not applications for future travel vouchers), and excluding any BA holiday bookings, one option is to PM to BA refund helper if you have been waiting more than a week https://www.flyertalk.com/forum/32267001-post259.html