O2 did not refund my initial payment after order cancellation

I ordered a MacBook Air from O2 on December 9. On December 10 I received the order confirmation and paid an initial payment of 209 euro via Revolut. After completing the payment I received an email stating that O2 cannot fulfill my order. The initial payment was already adjusted and deducted from my account. Today is December 21 and I have still not received any refund. I have sent multiple emails to O2 but have not received any response. I am requesting a refund of my initial payment or a clear update on the status of my case.