Kiwi.com complaint: we were not allowed onto the flight

Myself and my family who are Ukrainians have purchased the tickets to Dublin,Ireland travelling from Warsaw, Poland. We have fled the war with thousands of Ukraininans. We could not find the place to stay in Poland for a longer term and have bought the tickets to Ireland as it is currently accepts Ukrainian refugees. The only nearest tickets which we could find were the tickets on Kiwi.com, all of them were with the transfer via London, Stanstead.The site allowed us to purchase and pay for the tickets and we have entered our passport details. However, were were not allowed onto the flight in Warsaw. We were told that we do not have UK transit visa and can not travel. Given the current circumstances we did not have a time to get such visa as it requires the biometrics taken. we were not aware of such requirements otherwise we would not buy the tickets.