Can you do a gentle fib and say you already 'give to this charity on a personal private basis away from work and that you therefore don't/can't give more'? Ok, so it's a fib, but it's one that saves you face.
Alternatively just say NO. It's your choice to give to charity, what, when and how much and if you don't like them and think they're questionable, then you shouldn't be feeling pressured into doing it.
Jackie, Peer Moderator
www.iqps.org