The filing date will be stamped on the original Certificate of Offence that the officer filed with the court, not on your ticket.
When you show up for trial, you can go up to the clerk before the trial starts and ask them to show you the filing the date on the original.
If it is indeed 10 days after the ticket was issued, then you can ask the clerk why it got filed, and then you can tell the prosecutor as well before the trial starts. If the prosecutor wants to still have a trial, then when the trial starts you need to tell the Justice of the Peace right away that the Certificate of Offence was filed 10 days after the ticket was issued and Section 4 of the Provincial Offences Act says "A certificate of offence shall be filed in the office of the court as soon as is practicable, but no later than seven days after service of the offence notice or summons." and therefore the charge should be dropped.