Ruined Experience

I am still waiting for my refund from Dec 24 2019 when I bought 2 tickets to Durban for morning flight and when I got to the airport was told that the plane was full even though I was on time. I was then transferred to Comair flight which was scheduled to leave at 1pm. This spoiler our trip especially my son as this was our first flight and our first trip together. I wrote numerous complaints after that but has received no response