Website error but the client needs to pay

While booking the flight online I inserted my name on adult 1 and my fiancé name on adult 2. Details were correct until I paid and suddenly the name of both adults were my fiancé. But my contact information remained on adult 1. I emailed mango immediately informing them, then waited a day and contacted them again. Absolutely no response, when I got to the airport Cape town, an utterly useless guest service just reply you have to pay for an name change, not even an sorry for the inconvenience. Pathetic. Mango won't see me soon and I will make sure everyone I know, will know mango are *****ing money from the public.