A charitable organization's exemption (or anyone else's that is initially exempt) only lasts until you specifically tell them to place you on their do not call list. Then they are bound by the same regulations as any telemarketer.
Telling him you're not going to donate anymore is not the same as telling him not to call back by placing you on their do not call list.
Wording/Phrasing is important - you MUST tell them "Place me on your do not call list" or they will twist and spin whatever you say so they can keep on calling legally. They are only interested in legal, not moral or ethical.
Tom Bradshaw actually answered, but then said he had the wrong number ???
Who is he and what does he want? Tried to return the call, tried over a period of 4 hours, always busy signal...