Poor service at Kulula airways

We were issued a travel credit via kulula for tickets purchased during lockdown 2020. We cannot book and make payment using travel bank. We wait hours to get assistance via their call Centre and when you do get through the agents can't assist. The travel bank expires on 2nd Dec for an amount of R3400 and as of 2 weeks we are unable to get assistance. We are frustrated that nobody at kulula can help us. We have sent emails to them as well. Highly *********** people work there.