Arda Wigs also does restocks on colours, they have been back order for this long because their factory shuts down for 1 month for the Chinese New Year.
They also don't ship any orders with a single back order item. But if that happen you can contact them to concel the order as well and replace them.
Their website doesn't have a inventory stock counter yet (It's a ton of coding to set up) your the have to manually mark the items out of stock on their site and you might of just missed the out of stock list.
I would contact them first about your order and they willing to to do refunds if they can't get your back order wig in your deadline.