No flight changes even though I paid for the option to change!

Paid extra to be able to make changes to my flight only to find out "Kulula is a budget carrier and changes are not usually allowed" plus no refund for the extra paid in this regard. 2 questions: 1. Why was I given the option to pay more if the service will not be available to me? 2. Why not refund me if you cannot give me the service?

In the end I was told I could make changes but would have to pay full price for the new flight as I would be refunded in 10 days for the original/initial flight?!?!?! why not use the money you are refunding me to pay for the new flight?

Never booking with them again.