Landlord Breach of Lease?

It really sounds like they made an honest mistake - they probably gave proper notice to the tenants in the proper apartment, and while I understand you feel uneasy about the surprise of finding someone in your apartment it was someone that the landlord clearly trusted to do work for him so while you didn't know him, your landlord did not just hand over the keys to a complete stranger.

If you're still feeling uneasy, ask the landlord if he'd mind installing a chain door lock or install one yourself and use it while you're at home. That way they can't get into your apartment unannounced when you are home.

Landlord said she made a mistake so what's the big deal? If he had keys to get in, he was legitimate. They have to give you 24 hours notice to come in normally. I dont see why you are so shook up about the maintenance guy coming in. This was a mistake. Your landlord or his agent are allowed to go into a unit for repairs or emergencies without notice. You have no cause to break your lease. You are over-reacting.

Get over it. It was an obvious mistake by the landlord and is NOT a reason to get out of your lease without financial penalty.

No, you cannot move out without penalty. This was an obvious error, and not intentional on the part of the landlord and not intentional on the part of the worker who entered. While your privacy was violated, such was not intentional, and you did not suffer any damages due to the error. You need to put this in the past and move on with your life. Chances of this occurring again are quite slim.

No, you can violate your lease because of an an accident that could happen where ever you rent. You rent a new place and it is just as likely to happen again at the new place. Accidents happen.