My personal information given to another customer

I have a savings account with Capitec bank, for the sole purpose of transferring money into it for savings purposes. No other transactions in or out occur in that account. So when I received a sms on saying R1800 had been paid into this account, I suspected that someone had made a transfer error. Some minutes later I received a phone call on my cell from an unknown person to me, informing me she had transferred money into the wrong account, being my account. What? Where did she get my cell number? I asked her where she got my number but communication was difficult and she kept on giving me her cell number. I asked her whether she was at a Capitec branch and she confirmed that. I asked her to get one of the Capitec personnel to phone me. Later a lady phoned me and introduced herself as Lindewe from Capitec bank and asked for permission to correct the transaction and transfer the R1800 out of my account. I immediately gave my permission. Later I received an sms confirming R1800 has been taken out of my account, but the remaining balance in the account showed that the amount had been reversed twice. Some time later I received another sms saying R1800 had been taken out of my account. I had to phone customer service to find out what is going on and was informed by Pontsho ref 792 147 40 that a correction was done on the second transfer and my account balance was now correct. To date I have not received a conformation sms of this correction. I want to know from Capitec bank what authority they have to give my cell number to another client, why I have not received a sms confirming the one of the double debits to my account has been reversed and confirmation that my account only has one amount of R1800 going out.