No reply on refund claim.

I recently was booked on RwandAir to fly from South Africa to Kigali. The flight was delayed from 16h00 till 06h00 the next morning. The result was that I incurred hotel costs for a "no show" and I am now for almost 1 month trying to get RwandAir to respond and refund me for the cost of hotel. There is just no response.