From a customer Facebook post:
This is the lace top of my JR HH wig, Sienna.
The wig fitter cut the lace, after steaming the knots. Can anyone help me figure out why the lace is suddenly wavy? I had been wearing my lace front entirely too low. Could that be the reason why it is wavy? Or, could this have been caused from the lace being trimmed? It no longer is flush on my hair line. The untrimmed area has hair that never lays quite right. I still like how it looks, but this causes daily challenges. All advice always welcomed.
Steam (boiling water and other high heat) can warp the lace. Remember that the lace on the monofilament is made of a plastic-like polymer, not too unlike the material that makes up synthetic hair. Just like steam can change the texture of synthetic hair, it can also change the texture of your monofilament. The bigger downside is that the polymer used for the monofilament lace can melt a little molecularly, making it really difficult to un-warp once this has happened. You can always try, though. The best bet is to lightly steam it again with a targeted spray nozzle (the Jon Renau wig steamer is really great for this compared to conventional garment steamers) and hold the monofilament taut until it cools. Do this in small sections.
There is generally little benefit to steaming the knots on a HH wig. That is more for synthetic wigs, since they can't be styled with conventional heat tools. Even then, you have to use a targeted spray to make sure you're steaming the hair and not the mono lace.
My guess: they used a regular steamer on your wig and not one made specifically for wigs.
It is almost impossible to get a concentrated, targeted spray with a conventional garment steamer. You can use those very nicely to revive the ends of straight wigs, though, since that doesn't require a targeted spray.
IMHO, those folks owe you a repair at minimum or a whole new wig because they've damaged it.
Hopefully this has been helpful :)