But what IS math?!?

I’m new to this call-center but not new to call centers. Got a phone call in today, her bill is $75. Her past due is $55 and her current amount due is $20. I am literally bashing my head on the desk trying to explain to her that she cannot just pay the $20, her shit will get turned off. I’m really trying to be nice to her and tell her she has to pay the $55, especially before the new bill cuts because we’ll shut her shit off. “But can I just pay the $20? That’s all I have“, is the fucking conversation we had for at least 20 minutes. I knew she was like at least in her 60s and sometimes I wonder just how people make it into their 60s without basic math skills. How do they not just kill themselves because they’re so fucking STUPID?!?!?!????