Jetabroad  - Available service

I was one of the many million people who had my flights cancelled as a result of Covid19. My flights were booked for April 2020 from New Zealand to Australia. Finally after 21 months I have received an email stating I can either retain a credit with the airline or have a refund.

The email gave me the two options, which is nice, however, there is no further information available as to why the refund amount is less that 50% of the credit value. I have exhausted every possible combination of their fees and it doesn't appear to add up. The biggest problem is that I have tried to contact Jetabroad with some general questions to ascertain the following:
1. A breakdown or reason for the substantial difference between the refund and credit values.
2. If there is an expiry date on the credit
3. Any other conditions related to the credit, such as a particular airline, domestic vs international,

When I tried emailing the customer support, I get the following response:
"Unfortunately we will not be able to handle your request via this email address. Please use the online help request forms here:"

When using the link provided, there is no means to ask any questions, just applications to change the booking details.

Jetabroad does not provide a customer service email, a phone number or any other modern means to get in touch. I can't be the only one going through this process with them and hope that by some means I will eventually be able to be in contact with them or have them respond to an email.