There is a mistake that has taken place in CET seat allotment sir.
Hello
You should email the about your situation here
keauthority-ka@nic.in
and tell them about your situation also you should attach the sceenshot of the deduction of the Rs500 from your account. You can also visit them or call them at the numbers given at this website
https://cetonline.karnataka.gov.in/kea/contact_Us.
Hope it helps.