My apartment’s Residents Welfare Association was recently registered, but things haven’t been smooth since. Even though I’ve paid my maintenance dues, I’m being denied access to the lift because I haven’t paid for unauthorized construction in the building. Is this legal?

This is likely illegal. While RWA’s can enforce rules for the building, they cannot deny essential services like lift access for unrelated issues like unauthorized construction, especially if maintenance dues are paid. You have the right to use common areas of the building as long as you adhere to the RWA rules and regulations.