***** out of my kids account

I open account for my 2 little daughter , 2 weeks ago I received a sms that R200 was withdrawn from my child account, when we went to the bank we was told sorry its a system problem, when the put card number in it go to someone else account, but they put account number its my child account, they took my child card at Newmarket mall in alberton, and promise to sort it out, apparently someone in Umtata that have the some card number and that that woman change the pin inside bank and then purchase at riverside spar for R53. something, and promise that it will sorted out, We still waiting for responds and money that they took from my child account, how can standard bank make a mistake like that, likely we only started for the kids and they didn't have more in they account, I am a customer of standard bank for more than 20 years, very disappointed really,