I have too many needs in my family, the local food bank, and the Big Issue seller. Never buy it at £2.50, but just always give him food, a few Bob, or one or two of the wife's fags. Nothing left to give.
I get a lot of these letters asking for money, it's how charities survive. I don't get angry with them, rather I choose one or two a month and donate and try to spread it out so they all eventually get some. Worse things to worry about imo.