No security guards at ATMS to help customers!!

I am a foreigner, currently in SA for business. Last Friday, I went to withdraw money at the Standard Bank ATM in Cavendish Square. Unfortulately, some guys that were in the queue in front of me jammed the ATM machine by putting a **** keypad on existing keypad in order to obtain my pin code. Everything seemed fine so after them I went to use the machine. Inserted my card and pin number, to my biggest surprise, my card was swallowed and the screen was reflecting \Invalid Transaction"and I also got a receipt after that reflected the same. I panicked and couldn't understand what was happening"