Tackle society fine notice

I live in Maharashtra and my society has issued me a notice of 10k rs for not taking permission for water pipe repair works on terrace. I did ask for terrace key and repair works in verbal communication with secretary and he did sent a watchman with me on terrace to monitor the repair works. During our conversation he did not indicate that I need to write a written application and now they sent legal notice to pay fine for 10k rs. What should I do now? Any help is appreciated.