I gave up giving to big charities many, many years ago, over 40 years ago I think. Like dave50 I concentrate on small local ones where everything I give is used positively e.g. food for the local food bank. It is collected by someone in the village, taken straight there and is distributed. Other charity donations are also equally direct and transparent.
I volunteer for Oxfam and have done so for over 15 years. I enjoy my work and we have a very good little bookshop.
But Oxfam as a big charity seems to be managed by people who have got no clue about anything.
They should stay out of politics and start finding ways to direct traffic to their website, we sell online as do other charities. Not many people know this.