Terrible service and lack of security controls

I have a credit card with African bank, since I joined them I was happy with their service but on Sunday I got an SMS for USD transaction on my credit card which I did not authorize, I immediately blocked the card so no more transactions could be used on my credit card, I phoned African bank to inform of the ********** transaction in which they said they will get back to me in 48 hours by SMS and they gave me a reference number, I also confirmed with the consultant that my credit card was blocked. Wednesday evening another USD transaction for the same value goes off my credit card and on top of that it put my credit card in to overdrawn. African bank did not get back to me regarding the first transaction and how did my credit card get charged again when its blocked and there was not enough funds to complete the transaction. Terrible service from African Bank, do not trust them with your money.