What should I do I was late to work due to traffic and because of that I have salary deduction?

My job starts at 6pm and I always go to work at 4:20 pm because I only commute most of the time I arrive at work at 5:20 pm but yesterday the Catholics have this kind of parade that people were dancing to wordly songs and having a parade of teens wearing dress like princess with heavy make up and tiara like they were on prom walking on the road so the traffic is heavy and I texted my coworker on 5:20 pm that Im late and that she should wait for me for my shift and she said that I should took a pic for proof. I sent it to her. They say that when you are late you will write a letter to your boss of how and why are you late and there will be deduction of your salary. And Im still new to my job. Its just annoying because traffic is never happen on road before but because of that dancing and people on road thats the reason why Im late and Im annoyed.
What should I do I was late to work due to traffic and because of that I have salary deduction?
What should I do I was late to work due to traffic and because of that I have salary deduction?
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