Unfairly treated because their Chat Lindi inconvenienced me...

I booked a flight with FlySafair and I wanted to change bookings through their chat Lindi after checking the possibility making changes I realize I was going to pay close to R1000 for a fight costing R458 and I asked chat Lindi not to proceed with the bookings. So yesterday I was surprised that I did not get an email reminding me check in. Went to check on the app and the ticket was changed and expected to pay the amount I refused to pay in the first place. On the app is no option to cancel that request and continue with my initial booking. Their argument is is I was supposed to go to the airport and sorted it out then. How do I proceed to the airport if I am used to checking in on the app. They know their robot is favoring them than their customers but they still the the customers use the service. I have provided proof that I did not agree to the R600 and it must not be changed... Why should a big company like FlySafair take from the poor... If I mentioned thar I do not have R600 that means honestly cannot afford it.