Update: Ryanair credited my credit card account with the value of the first booking today.After months of checking my credit card account in expectation of my refund, I tried the chat service again today an, surprisingly, I got a Customer Care agent today. He advised me that, as I had not requested a refund for the second time, on receipt of the voucher email, I was not in the refund queue. He said he would request the refund for me and it should take a maximum of 6 weeks. We'll see!