What can I do about my apartment landlord refusing to give me my mailbox key now for over 30 days

I have asked for my key to my mailbox now for over 30 days and I've asked for the past 17 days consecutively and each time I've been given the excuse that it's already made that I need to meet a certain maintenance man at a certain time that never happens then I've been told she left something at work blah blah bl ah and then I was told as of recent that she needs to have the box open first that way she can fit something special into there to get the key fitted and then send it off somewhere and this is after telling me for 30 days that she already had it made so she's lied to me it's time the kicker is I've had time sensitive documents in there that I've told her since the very first message that I need to get to that she just does not care about and at this point that time is expired and he's causing me more problems than just being able to open my mailbox to throw a junk mail and Ive explained that to her and as of two days ago now she just quit returning my messages. What can I do