Avoid this airline at all costs (or it will cost you)

Booked a ticket (aprox. R600) and paid additional for travel insurance which is meant to cover cancelations (per their website popup). Realised I booked for the wrong day but the app & website would not allow me to cancel (suspicious) so I ended up transferring my flight (R300 transfer fee) and booking another which was cheaper than the original flight (approx. R500) but I had to pay the full R800 for the new ticket and they kept the R600 from my previous ticket. The website said I only had to pay the difference, in which case they would have owed me R100 yet I was charged a total of R1400 and have yet to see a cent refunded nor am I able to contact them. At this point I don't even want to speak to a representative just to be told "there's nothing we can do". Jusy pay me what you owe me :)