YANBU not to want to be harassed but YABU to do a
face after talking about marketing, LadyS. Charities are not just businesses, they are fundraising organisations to combat specific problems, so of course they are 'marketing' - aka letting people know what they do!
Cancel the DD if you want to, but personally I think it's a petulant response. DP is a charity fundraising manager and those people get crappy wages and work all the hours that God sends trying to keep worthwhile causes afloat in a horrendously difficult market. Of course they are trying to keep people giving, it's not some kind of self-perpetuating scam, they are trying to keep money coming in to support the good work they are doing. When govt grants are being cut and loads of people are cancelling DDs due to losing their jobs, they have to make sure they are careful keeping support going.
If you don't believe in the charity, cancel the DD.
If you do, continue to give what you can afford, but fgs ring their fundraising officer directly and talk through your concerns! Some charities do outsource these phone calls, so if the people they're employing aren't getting it right, they need to know.
I don't think flouncing is particularly helpful in this situation.