I strongly dislike an elderly woman

I know, it's horrible and I feel horrible about it. But I have never met such a mean person in my life. There is an elderly woman who comes into my work every couple of weeks and every time she comes in she yells at me about something. Mind you I am the concierge, all I do is answer and transfer phone calls and point people in the right direction. I do not make the executive decisions around here. So lets start from the beginning.

Most people walk in our building and look lost so my main job is to ask them if I can help them find where they need to go. Well this lovely lady walked in with her walker and I told her where she needed to go and she immediately started yelling at me that "the sick people shouldn't have to go all the way upstairs." I work at a clinic, everyone here is sick and we have an elevator. Nonetheless I told her I was sorry but that's where the office she was looking for is located. After her appointment she came back downstairs to the lobby to wait for her ride. I asked her if she would like me to get her some water and she said "yes." When I returned with a bottle of water she started yelling at me telling me that "the water is too big, how would someone ever finish all that water, it is such a waste!" Keep in mind it's a standard 16oz water bottle. I told her she could take it with her, that's what most people do, she didn't like that answer. She then preceded to complain about how our chairs are too soft and are made for "short people." I told her I was sorry and that I could get her a metal folding chair but she told me "NO."

On our second encounter she once again complained about the chairs being too soft and to low. This time she also complained that the elevator door does not stay open long enough. I replied by telling her there is a button she can hold down to keep the elevator doors open...she didn't care.

I was lucky enough to see her scowl ridden face yesterday. I thought perhaps she would be in a better mood, with the holidays coming and all. We even have our Christmas decorations up in our clinic. In the lobby we have a huge tree, which a outside company comes in to decorate and it is just beautiful. As the bundle of happiness was leaving I said "have a nice day!" to which she looked at me and replied "THE IS THE UGLIEST TREE I HAVE EVER SEEN! IT IS HIDEOUS!" I was honestly caught off guard, I mean who insults a Christmas tree? So I replied "well most people really like it." "Well it is just awful" she said.

I am hoping next time she will insult me on my growing belly or perhaps complain about the donation box we have for need children.

I am open to taking any witty come backs you all might have.