Two apt. problems: Mailbox, mice.

So all at once this winter I had 2 decently major apt. problems at once, to the point where I had to call my landlord:

1) No mail for a week...  I was wondering if it was snow on the sidewalk and had been meaning to call USPS customer service, then I ran into the space-y neighbor from downstairs at the coffee shop on a Sunday and he said he saw the mailman banging on the box and the guy said the main lock wasn't working from the cold.

2) The day after, I'm in my kitchen like 10am by the stove putting on some coffee, and I see a mouse running along the corner of the room.