Unauthorised transactions allowed by Absa

On Saturday at 00:03 midnight my card number was used to do transctions worth R1500 amount, I only got app message on my phone that says" transaction has been done from your account'. Tried to log in to my app to see the transactions and boom my app was not working, it just froze since that time. Sent an email because of my network I couldn't call, then tried to check using my internet banking but the transactions weren't appearing. I have then sent an email but Absa is not responding since Saturday and called yesterday again there is no response. All I said is I want my money because transactions are supposed to authorised by my myself on my app, and this was not the case. My question how did this go through? Please assist. My app was not working since then I deleted it today and downloaded again.