Takes moneey but does not confirm booking

I have tried twice to book on BA website return flights from JNB – LHR without success. I used my credit card on Monday 29 Jan and waited until 4 Feb for money to be released by BA. When it was not released on 4 Feb I used another credit card and paid again (R 4000) more expensive and again the money was passed byVisa to BA but the booking was not confirmed. I had numerous telephone calls without success. BA has now sterilised nearly R 80 000 without confirming a booking and in th mean time the prices keep going up.