Frustrated due to lack of fast communication channels.

I have been trying in vain to use my credit from a flight I had to cancel. They have no other way of contact apart from email and WhatsApp. Booking a flight means communication and getting reply emails, answering them and waiting for a response has taken weeks! The service agent doesn't read the email properly and just send something like - please confirm this or that. So I reply and get a response back after 2-5 days giving me another one liner answer. Its the longest conversation I ever had! I have to use my credit before year end and I stared this process well in advance. Now I might loose my credit and I am really, really frustrated. I wouldn't use a travel agency with no call centre again! Especially NOT travel start ( They had one but decided to change their way of communication) I live in New Zealand so please add the +64 code to my mobile number.