If the Court had dismissed the case with prejudice, the suit could not be brought again.
However, this is very unlikely, and a dismissal for failure to prosecute will not bar the plaintiff from bringing the same suit on the same facts/bill again.
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I agree that it depends on the type of dismissal that was granted, with or without prejudice.
Either way, I would point out to the company that sent you the letter that there was already a lawsuit filed on these bills which was dismissed. Sometimes the debt is sold from one company to another and the company contacting you now may not be aware there was a prior action filed.
If the company goes ahead and does file a new action, you should certainly answer the complaint and/or appear again for the return date (depending on what your country requires in small claims cases) and assert that a previous lawsuit on these same bills was already dismissed. This may or may not resolve the whole issue depending again on the type of dismissal.
Unfortunately you will not receive compensation for the lost wages incurred in this. Best of luck.