Cut out their food supply. The only reason there are so many is because there's either too much food the fish can handle, or the trumpets get to it undisturbed. I have cherry shrimp and bottom dwellers(corys, khuli loaches, plecos) and despite having 3 types of snails, their population is unnoticeable, including the prolific trumpets.
I had a trumpet snail explosion in the summer in a cherry shrimp only tank which I overfed. Eventually the trumpets became so many and so bold, they'd come out immediately at feeding time alongside the shrimp piling over fallen wafers, climbing on the zucchini, etc... I just stopped feeding that much and their population dwindled. But it's a lot easier in my fish tanks because the fish get to the food first.
If you want to get rid of the trumpets completely because they uproot plants(never happened to me), then assassin aren't any better because they'll dig in the substrate too and once they've munched on the other snails, they'll happily accept fish food so I just don't see the logic of replacing one snail with another. At least trumpets are more useful than assasins and mine are quite beautiful, light brown with black dots/stripes.
But assasins will get rid of them alright.
This video is disgusting but quite funny. Trumpets eating algae