Deeply grieved, unjustified and let down

********** transactions went off frm my credit card o 26-28 June 2015, i received a notification sms only on 28th to confirm about 2 transactions & I declined. On the 29th I went to a branch 2 enquire, I spoke 2 one of the consultants over the phone they advised that somebody was using my account but the transactions did not go through as my account has a limit of R5500. On the 1July a msg frm the bank confirmed that theres no need for a case as the actual ***** did not take place but rather an attempt so the case is closed. Later on it's changed, the transactions went through & I'm responsible bcos the actual card with my pin number had been used? Im grieved deeply, literally in tears & feel violated not only by the ********** but mostly by the bank, what a dishonour, they refuse to take responsibility & accountability. I did not make these transactions, No one is looking at the FACT that this account had a limit, initially advised me these transactions were unsuccessful & the system detected that this is *****, I am a victim in this case. Hw re they not responsible for securing my acc? Why is it my fault if system failed to avoid transactions to go over the limit?