It is OK that you sent letters to the creditors about filing bankruptcy, but that wasn't necessary because when you file bankruptcy the court sends notice to all of the creditors you have listed in your bankruptcy.  Filing bankruptcy prevents the creditors from taking any legal action against you.  The calls should also stop.  If the calls from the creditors are continuing, this is probably due to the creditors not yet having received notice from the court of your bankruptcy filing.  When the creditors call, just tell them the date you filed bankruptcy and give them the case number.  That should stop the calls.