Not refunding transaction

I booked a flight in February to travel in March. I received an invoice and the transaction showed on my credit card statement. Closer to the time of the flight, Kulula could not find the reservation and I was advised to book a new flight in the meantime until they look for the problem. After numerous phone calls and e-mails between Kulula, the bank, and me, I received an e-mail from them on 5 May, stating that the refund was 'assigned' and that I would hear from them again in 3 days. On 22 May, I rep**** to the e-mail, because I hadn't heard of them. I still had no reply.