FlySafair dont care about passengers checking in

I booked flights for my family and on arriving in check-in queue, we were told to step forward as the flight was closing. Whilst checking-in we were told that the flight is closed despite having been asked to come forward and being 45 minutes prior to departure at the airport. The on-duty manager refused to accept the matter and told us to "go fly a kite". We had to rebook on Mango at a cost of R2900 as we were attending a memorial service in PE. FlySafair's Tebogo Tshoma now emails me that they will not refund me the lost flight. This is a terrible airline which I will never use or recommend to family, staff and public.