Computers are used in all sorts of different environments every day, ranging from homes, shops and bars to warehouses and office buildings. I am pretty sure that the atmosphere varies greatly in all these places, and that variables like cigarette smoke and dust really can’t be a reason to void warranty on computer equipment. If it was a reason to void warranty I am pretty sure there would have been a big uproar over that already a long time ago (I’ve seen some very dusty and smoky warehouses in my day!).

Smoking Apple users I hope this gets resolved properly, and that you get the service that you have paid for.