Kulula failing to refund after 7 Months

I have been waiting for a refund from Kulula from September 2021. I received a reversal letter from them today 12 May 2022, which my bank cant use because it is not relevant to the transaction. When I emailed the agent giving her feedback from my bank she told me that her team leader is saying that is the only way they do refunds and sorry for the inconvenience. So Kulula ***** money from their clients claiming that they are not able to refund money back into my account. Can I be advised what to do next please. I really need this money to be refunded.