The only thing I have had work for me was a matted file fish.
I tried all of the chemical products ( for years), tried berghias, ( worked somewhat in smaller tanks), tried peppermmint shrimp ( never worked at all).
I bought a matted file fish and put it in my 240 which had hundreds of majano's and aptasias. I thought this was a bust too, because I didn't see any difference after a month. But a little after that, I noticed a area that didn't have any, then other areas, and by the end of 2-1/2 months I couldn't find any majanos or aptasias.
I moved the file fish into another tank that had a small problem and he cleared them out. I left the fish in that tank for 4-5 months, just to be sure. Then I moved it to my 240 sump which had a pretty good population of majanos in the chaeto. He is still there.
So it's been a year and I did find one aptasia and one majano, which I just moved the small rock they were on into the sump and the let the file fish eat them.
Not bad for a $25 fish.
I easily spent 10x that amount in out cures that didn't work for me.