Voucher dispute

Good day.

I am writing this review in regard to the lack of assistance from Kulula. I booked a flight last year before Covid had happen. As we know all flights were canceled. I then requested for a voucher so that I could use it in the future. They responded and gave me a voucher valid for 12 months. However, 3 weeks ago I decided to use this voucher (taking into consideration that the voucher expires in April) . I phoned the company as I could not book online, it did not want to accept my voucher. The gentleman that assisted me said he will send an email to his supervisor and once the supervisor give the go ahead then they will have to send it to another company as they don't fly to the destination that I require. A week went by and nobody responded. It's been 3 weeks and I have phoned and emailed Kulula 3 times already. They give me the same response. I am tired of waiting and requesting for assistance. Something must be done!!