DEBIT MY CARD THEN SAY THE SEATS ARE NOT AVAILABLE

I tried to book a flight on the 5th via the Discovery portal. My card was debited then a note popped up to say that \your selected flights cannot be reserved". Tried again then only for that flight the price went up R800. Tried different time. Money taken off and the same message popped up. Phoned Kulula. They said that the seats were all taken. How can that be? They still take my money. Phoned Discovery. Matshepo comes back to me to say that Kulula had a problem and that it is resolved. I tried this morning and the same problem arose. How can they suddenly change amounts"