Can You Do a Partial Chargeback on a Credit Card Payment?

I've been caught up in the AirAsia Melbourne-Bali flight cancellations and am getting sick of waiting for the refund they have judged to be valid.

We had flights to and from Bali cancelled, but they did rebook us on the initial flight via KL. On the return leg they offered a refund which we accepted and came home via another route (for more money). We applied for a refund, and had the approval accepted over a month ago, and was due to fly 6 weeks ago. I've chased it up multiple times via different channels and I am getting nowhere, and this seems a relatively common complaint.

I paid on Visa and was wondering if I could lodge a chargeback for the 50% of the flight that I am owed.

Any advice would be appreciated

Thanks