Non iron polyester - full of creases - please help!

[SmallBee]

Ok, I am probably being an idiot but I don't know what to do here. I've brought a nativity costume for DD for her play on Friday. Its come in the post and it is FULL of creases. Of course because it is cheap and cheerful it is not to be ironed, and the only way I can clean it is with a damp sponge.
Is there any way I can get these hugely visible creases out before Friday please?

Biggest lie sold to man is non iron fabrics (besides stainless steel).

Anyway best thing to do, is hang it in the bathroom and run the shower (or taps) on hot, shut the door and window and let the steam build up in the room - may take a good 10 mins at least though.

I don’t know if they still sell it, there used to be a wrinkle releaser spray you could get (a bit like febreeze but not that iyswim), but not sure if still around, obscure places like home bargains or wilko may have it under an own label.

If you’re willing to pay a £5. American version here

Dry cleaners would be able to steam out creases for a couple of quid.