Poor Service from this airline - I want to rebook or a refund

I have been trying to call Kulula for the last 3 days - average waiting time 40 minutes and no answer. I have flights booked from July which I want to reschedule. Raising a complaint does not work and clearly no one works there either - how disappointing as I have flown with them many times.... I want my flight rebooked or a refund so I can choose another airline