“Both the Tanach and the gemoroh explicitly endorse giving tzedokoh in the hope of a reward”
True, however, there is no mention that a particular gadol must daven on behalf of a donor of a particular amount, donated at a specific time and date. Tzedaka, is tzedaka is tzedaka, and the rewards promised by hashem will come, no matter how many glossy page ads promote or dont promote the receiving organization or receipient.