Kulula poor service

After spending more than 2 hours on the phone finally got through to customer care then the drama started. They were helpful to change my covid19 tickets to a later flight at a cost...which was fine however then they phoned back two laters to say that I have to pay even more. Requested that they give me the money in my travel account which they then were unwilling to do. I dont want my money back I just want them to allow me to reschedule. They are not going to lose money as the flight is only in April 2021