Rude Cashier

I went to bp this morning at about 4:08 am to buy engine oil I was badly treated by a lady cashier. I stood outside at the window waiting for her to serve people that were inside but while she was done she just stood there as if she did not see me. I politely asked her to help me but she attacked me with words telling me she only has two hands. What the hell is that? People like that lady cashier must be removed from jobs that deals with people. No customer service at all.