Write a short, polite but forceful letter to the City of Toronto requesting they waive their assessed penalty for late submission of the annual home vacancy declaration, which was impossible to file due to an overwhelmed web portal and incorrect backend data for my home.
To Whom It May Concern:  I was unable to complete the filing of my home vacancy declaration by the deadline, and was assessed a penalty for the late submission. I faced numerous problems during submission due to your overwhelmed web portal, and even once I passed that barrier, I then faced incorrect data about my account that made it impossible to complete the process.  I would appreciate if you would waive the assessed penalty due to these circumstances.  I sympathesize with the difficulties you faced with the roll out of this system, and look forward to what will surely be a smoother process next year.  Sincerely, Signed.