I want nothing to do with standard bank

Yesterday(14/02/2016) I checked my balance using Standard bank app only to find out that there was a transaction of R1500 that went off my account and I have no knowledge of. And today I called the call center and Spoke to Chantel from ***** Dept who told me that the transaction was made on the 10th December 2015. not only do I not know anything about the transaction but why after 2 months? I have been banking with Standard bank for 16 years and I never had issues until I converted to a cheque account. I want nothing to do with standard bank and I want my all my accounts to be closed included the investments I took with them. My account is not safe and I have absolutely no control over my funds.