Poppa, all segulos work assuming you have the right kavanos and you follow the instructions to the letter. It took me months to get my silver segula ring of power correct from following the footnote in the kav hayashar, and the +hit and +dam values are still off.
You must remember that the aravos represent those who have no Torah and no mitzvos, and are thus easily affected by the havlei olam. The more exposure to hevel, the worse they are. So the segulah is a 3-parter:
1. the foil must be long enough to engulf the entire aravos to protect them from the havlei olam , and the Aravos must be kept in them at all times when not in use to minimize exposure to the tum’ah of the olam.
2. Torah is compared to water, and the aravos desperately need water to minimize the pernicious effects of the havlei olam. so the foil must be lined with a wet paper towel long enough to engulf the entire aravah. If the towel dries up, the water must be replaced.
3. Hislahavus is great for tefila but bad for learning, which is best done with a kerirus hada’as. So the package must be stored in the fridge, and (this was probably your mistake) the FRIDGE MUST BE PLUGGED IN.
Finally, letting your wife borrow your arbah minim seems to cause the wilting to accelerate. This is for one of 2 reasons:
1. Women, as they are on a higher spiritual plane, do not understand how exposure to the havlei olam hazeh ruins the amei ha’aretz represented by the aravos. So they leave them exposed to the hevel more than they should be.
2. “bah isha, ba satan” has a very bad effect on amei ha’aretz who don’t have Torah to be magna umatzla. so mere exposure to women can wilt the aravos and make them meisim afilu bechayeihem.