Dear expats, i forgot to do my 90 day report ehich was due on oct 20th, what can i do and what will be the consequences of my negligence?

I was fined 1600 baht today while doing the paperwork for my medical visa extension. It was when I was filling out the T30 form. His english was very poor and I couldn't understand but he said something about my address and registration. He said the last time I made a border run I needed to come and tell immigration in person when I reported back. I asked my landlord and she confirmed that I was already registered at the room by her. Any ideas?