Advice: Is this Illegal, unscrupulous, or usual practice? (feel like i got mislead by agent)

I contact agent A about apartment 1. She offers to show it to me, as well as apartment 2 in the same building (her suggestion I did not request to see it).

I view apartment 2 with her and mysterious agent B shows up (not sure who they represent).

I like apartment 2 so I apply for it. I am to be charged 15% fee by agent A.

I have not paid anything yet or signed any contracts (but I submitted the application and acknowledged the fee).

I just looked online and see that agent B has listed apartment 2 as No Fee. Agent A is going through agent B and charging me 15% fee when it's listed as No Fee.

Now, this seems slimy as hell to me. What should I do?