Poor result of slightly pathetic complaint

This is just a thing that is bothering me. I want to know if anyone has ideas about how I could have done it more successfully.

I was in a trendy coffee shop on my own. As I sat down the waitress gave me menus and asked what I wanted to drink. Coffee shop not very full, 2 waiters in the area. Breakfast time. I asked for coffee which was quickly brought, not asked if I wanted anything else then left alone for 40 minutes. I did have a book open but was looking around for attention after about 15. Eventually made strong enough signs that the waiter came over. I said "I know I'm a woman of a certain age and therefore invisible but I would like another coffee and something to eat. I said it gently and with a smile. His face hardened and reddened with what looked like anger. He barely listened to what I wanted, some sort of fruited Danish and said there was nothing like that. Brought me the coffee but couldn't get away fast enough.

I wanted just to remind him to be aware of all customers. What would have worked better do you think?