I echo what @DiscoStu said - a multi-pronged approach is the most likely path to success in such a large tank with a reasonably advanced infestation.
I can't say that I've personally observed a bumble bee snail prey upon a vermetid, but anecdotally they do seem to help reduce the population over time. You probably need at least a couple dozen in a tank that large to outpace vermetid reproduction. I would try an electric blue hermit as others have suggested.
As a second prong, I would try to physically remove or destroy any that you see, using bone cutters. It's very satisfying to remove huge vermetids that reside in nooks and crannies previously unbeknownst to you. Be sure to destroy/detach their bases and not just the spires, as the vermetid resides in the base and can reconstruct a busted spiral pretty quickly. Note that they will pop up everywhere, including in your sump, overflow boxes, etc., as they spawn regularly and have absolutely no need for light.
As a third prong, I use coral snow, which can actually help identify larger vermetids for physical removal, as sometimes you can see mucus nets emerge from unexpected spots, and they're easy to see when chalked up. I think the idea behind treating with coral snow is essentially that you fill the vermetids' stomachs with nutritionally useless chalk and slowly starve them to death. However, for this strategy to be effective, I think you'd need to (a) consistently dose the coral snow once or twice a week for several weeks and (b) cease any broadcast feeding you're doing (reef roids, phyto, etc) for the duration of the coral snow treatments for this purpose.
One tip I would offer for coral snow treatments for purposes of vermetid removal is to do what you can to stimulate a feeding response a few minutes before adding the coral snow. Something like polyp booster or feeding the fish can stimulate the vermetids to cast wide mucous nets, and then they gobble up the coral snow just as you want them to do.
