harrassment from a payday loan company for $350.00

i was just wondering, i had originally owed a paydy loan company 350.00. when i went to refinance, i decided to make it a 500.00 dollar loan so i can get the xtra 150.00. the problem is, i had forgotten my checks. the lady said it was okay just to bring the check another day, that she would use the old check of 350.00. needless to say, i defaulted on the loan and now she is calling me 5-6 times a day. she said she will lose her job if i dont pay her. that she doesnt care if the check bounces that she just needs that new check. if i dont respond, she said she will come to my home or place of work, and that it can and will be taken to small claims court for payment. my mother called me and said she has been calling her house telling her that i havent brought in the check i owe. also, my job called me saying she called stating that it was family emergency and i should call her back. this is so embarrassing but now i am getting very mad at this womans tactics. is this even legal? is the 350.00 dollar check any good? can i do anything about it?