Is accidently writing a bad check reason for criminal charges?

The specific answer to your question depends upon the state you live in.  Most states have recognized that having a check bounce (especially to a payday lender) is not criminal because there is no "intent" to defraud.  Also, the debt collecting attorney has no power to "file a criminal charge."  Only the government, through the prosecutor or the police, can do that and most of them would take no interest in a matter like this.  Law firms collecting debts qualify as "debt collectors" under the Fair Debt Collection Practices Act (FDCPA).  It is generally considered an "unfair and deceptive act or practice" for a debt collector to threaten you with criminal prosecution or to attempt to collect a "stale" debt.  KEEP A LOG OR DIARY OF THE PHONE CALLS AND WHAT IS SAID so you can document the threats, and find out the "statute of limitations" in your state for this kind of debt to see if its is "stale."  Under the FDCPA, you have a right to tell the collector to stop contacting you and those associated with you (like your employer, or neighbors, or family members).  Do it in WRITING.  Date, sign, and keep a copy and reference the account name or number.  Finally, in most states, there is nothing an unsecured creditor (where the debt has no collateral like a car loan or home loan) can do to you unless they first sue and win a court judgment.  After a court judgment, the law of each state gives you levels of protection (called "exemptions") in your income and assets to keep free and clear of your creditors, including creditors with court judgments.  Finally, this debt can be wiped-out ("discharged") in bankruptcy, if you reasons for considering bankruptcy.  Hope this helps.