I called a non toll free scam but I closed my laptop and went to sleep... i open my pc and try to call again it says coin balance is not enough then i see -460 but the scammer had hung up please refund
try only dialing toll free to build your account up.
This is not a bug. You called NTF numbers which cost call tokens, as WhiskeyTangoFoxtrot said, you can earn call tokens by dialing Toll Free numbers.
I granted you some call tokens to bring you out of the negative.