Hi Sammy
You must get everything in writing. The executive committee is not giving you a consistent story. Please put together all emails, text messages and paper correspondence to confirm what you are saying. I hope you have a written statement from your workman from five years ago.
From my own experience in NSW, you cannot claim that the owners corp “refused to fix something” unless you first ask them to do it. If you have not done so already, put your request in writing. Then get their response in writing.
Then ask a strata lawyer how you should proceed. I don’t know why you would be liable. A strata lawyer can advise you.