If the carrier has promised a refund and it has not been initiated within a reasonable time period, you should initiate a chargeback with your credit card issuer. Make certain that you provide in the notes that the carrier has agreed to a refund but has not followed through. The impact of this is that, at worst, when the chargeback is forwarded to KE for a response, it is immediately seen that a refund is due and thus no effort is wasted "investigating" whether KE ought to contest the chargeback.