payday loan

i tried to take out a loan to see if i get it because i needed to pay off my overdraft bank account. i didn't know i got until they called me asking me for their money. i didn't check until about the end of july begging of aug and now its up to $500 and i don't get paid until i go back to work. then i don't get paid until oct 15. i didn't know i got the loan. mon they are going to call me back and expect the money. what can i do i don't have any money.