Travelstart's system working in different ways leading me to double book with impossible dates and costing me thousands of Rands

I was booking for a return flight to Jhb from Cape Town, I have used Travelstart for many years. As I got to the wait for bank verification, I expected to get a screen about bank verification but was suddenly shown a screen saying that my booking was successful. Well. I was certain at that point that their system was at fault as it clearly said it was taking me to the bank screen. So I forgot about that one, as it was obviously not verified by my bank, and booked another , this time the same message came up about the bank, and I got told by the bank screen to enter the OTP their system had sent me, which I did. So then I found out that both bookings in Travelstarts side, were valid. How can that be?? I have been in contact with them, asking them to cancel the one that DID NOT GO THROUGH THE BANK VERIFICATION PROCESS and they kindly offered me +- R400 for the first ticket that I was sure did not go through as their process did not follow even their own instructions. So, we are in deadlock. Then I got 4 e tickets for 4 different flights!!! Talk about a huge bug in their system. It so happened that there were 3 flights booked, but they have conveniently not spoken of that. Who booked the third one?? I know I didnt. So I have to take this as far as I can. I have the time, and being in IT for 43 years, I know that a system works one way and should always work in the same manner, however, the first flight and the second flight did not follow the same pattern. Anyone else in development spot a bug they refuse to acknowledge??? Their explanation does not even make sense, something about a 'the only time clients are requested to verify with their bank is if the payment that they are doing is a 3Dsecure payment' so why then did they ask and send me to the bank verification process on the second booking and not the first time. And why would I book flights that overlap anyway. I changed the dates on the second to give myself extra time in Jhb, and would have to run all the way back to Cape Town to catch one of the flights. Surely they can see this was their system not giving me the proper assurance that the first flight did not need bank verification?? However, then why did the second ask for bank verification which is NORMAL and I expect this, their screen even said wait for bank verification on the first flight but that never happened leading me to think that there was a fault somewhere. I am sadly disappointed that my favourite booking system has bugs in it and advise others to watch out for this too. Oh, and all the paperwork they sent me, booking for 4 different reference numbers, talk about being confused. and they still think their system is bug free, I think not. After 43 years in IT I can spot a bug a mile away, but apparently they refuse to see the logic, which is missing obviously