Why is a bank making cash withdrawals on customers accounts.

Today an amount of R2000 was withdrawn from my account. It was 7:56 am. Without my knowledge this was done. I received an sms stating Capitec withdrawal R2000. Firstly I went to the branch on the bluff but they were closed for business today. I thereafter phoned the contact centre to query and apparently on 2nd February 2020 I made a withdrawal at an atm and the money did not get deducted from the bank on that specific day as their system was offline . I cannot remember ever having my bank account go into an overdraft or a minus. This is a savings account. so the call centre agent told me that after doing their audits they picked up on a few accounts that withdrew money that day and are correcting the errors by taking back their money. I'm confused why 2 months later why not immediatly after the system rebooted did they not correct it. I have not received any help concerning whether I will be reimbursed but I'm not happy. Please help