Both the Tanach and the gemoroh explicitly endorse giving tzedokoh in the hope of a reward. Calling it “avoda zara” is outright apikorsus.
If it seems to you like a theological problem then the problem is with your religion, which is clearly not the religion of the Torah, so you need to examine your own hashkofos and abandon those that contradict the Torah. Specifically, the hashkofoh that has a problem with segulos is Protestantism. It is a European creation that infected Xianity, and through the Haskolah it reached into Yiddishkeit too, particularly in Litta.
Edited to fix tags – use strong and /strong