Post office Meyersdal staff is so rude

I visited the Post Office in Meyersdal this morning hoping to renew my licence disc, when I arrived at 08h00 the door was opened and i entered the door, however the two lady's (staff) behind the counter shouted at me telling me that the are not yet opened... they were so rude to me it was like I had ****** something. My questions is, why did they open the door if they are not yet ready to work, and why do they shout at me as if I am the one who unlocked the door.