Straight wig to curly: Does the "boiling method" lead to permanent results?

[AGAssi]

Hey guys,
with my last two wig orders, I've been facing the following problems: The wig arrived in a nice curly (but not frizzy) style, but after the first shampooing and conditioning, all curls vanished and the human hair wig is almost straight now, just slightly wave. (all other orders over the past years kept their curls even after washing like a 100 times)

I need this wig (rest is perfect) to be a curly style which I can wear permanently, have a shower, sleep, sports with it and so on.

So I was looking for some tutorials on "permanent waves", and ended up finding the "boiling method" (with beautiful results) which seems nice to me because it doesn't use chemicals, thus less damage to the hair, I guess.

But as people are mixing the methods of steam processing (for 15 minutes) and boiling (for up to 2 hours), I wonder if any of these methods is permanent in terms of keeping the curls for months with daily showering, shampoing... or is all this effort only for wearing on a daily base with NOT (never) washing it afterwards? (I have experience with simple "blow-dryer curls" which only last till next washing)

So, in the end, is the boiling method a suitable alternativ to a chemical perm and remain curly (like 3+ months) also after shampoing?