you wait forever for them to get back to you

I mistakenly made an error by booking 2 different tickets for the same passenger for the same flights, same time, same time and same destination. I called the airline immediately to inform them about my mistake and to get a refund for the one ticket. They make you hold on the line until forever. When they eventually get back onto the line they say they will phone you back, but obviously that does never happen. When I eventually got hold of them they say they will only refund me 50% of the amount paid. I mean seriously ?? they are actually *****ing the other 50%.. this is ridiculous, I will never ever book with kulula again.