Flowerlady

Hi all, I couldn't figure out how to introduce myself but we've renovated a 17th century terrace almost finished - ish. We've had double glazing put in & the agreement was we'd have no trickle vent in the living room window as we would have one in the other window in that room - at this point I had no idea there were exemptions for conservation areas & the company didn't tell me. On the contract all other windows mention the dreaded trickle vents but the living room window does not. Basically what I would like to know is should I expect a full window replacement or a blanking plate to remedy this? I'm concerned about the noise they allow in as we're on a busy high street. The windows are beautiful, look like the old originals but they've cost a fortune & I feel a bit miffed. What are your thoughts?