Double charge for using a different ATM

I called FNB and spoke to Queen Motloung regarding a payment that I received yesterday but the R45 was missing and nowhere to be seen on my statement, she explained it a service fee from last week when I withdraw money at a different ATM, so I asked her if I'm being charged immediately a service than what is the other service fee for that I get charged close to the end of the month when I'm being charged a monthly fee, she said it's the same thing. She basically confirmed that I'm being charged twice for using a different ATM. So my question is why do I charged twice for it????